Functions

Table of Contents

• Informational Functions

  • active_branch()

  • dolt_merge_base()

  • hashof()

  • dolt_version()

  • has_ancestor()

  • last_insert_uuid()

• Table Functions

  • dolt_diff()

  • dolt_diff_stat()

  • dolt_diff_summary()

  • dolt_log()

  • dolt_patch()

  • dolt_reflog()

  • dolt_schema_diff()

  • dolt_query_diff()

Informational Functions

ACTIVE_BRANCH()

The ACTIVE_BRANCH() function returns the name of the currently active branch for this session.

https://www.dolthub.com/repositories/dolthub/docs_examples/embed/main?q=select+active_branch%28%29%3B

DOLT_MERGE_BASE()

DOLT_MERGE_BASE() returns the hash of the common ancestor between two branches.

Consider the following branch structure:

      A---B---C feature
     /
D---E---F---G main

The following would return the hash of commit E:

https://www.dolthub.com/repositories/dolthub/docs_examples/embed/main?q=SELECT+DOLT_MERGE_BASE%28%27feature%27%2C+%27main%27%29%3B

HASHOF()

The HASHOF() function returns the commit hash of a branch or other commit spec.

https://www.dolthub.com/repositories/dolthub/docs_examples/embed/main?q=select+hashof%28%27main%27%29%3B

DOLT_VERSION()

The DOLT_VERSION() function returns the version string for the Dolt binary.

mysql> select dolt_version();
+----------------+
| dolt_version() |
+----------------+
| 0.40.4         |
+----------------+

HAS_ANCESTOR()

The HASH_ANCESTOR(target, ancestor) function returns a boolean indicating whether a candidate ancestor commit is in the commit graph of the target ref.

Consider the example commit graph from above:

      A---B---C feature
     /
D---E---F---G main

A hypothetical example where we substitute letters for commit hashes would look like:

select has_ancestor('feature', 'A'); -- true
select has_ancestor('feature', 'E'); -- true
select has_ancestor('feature', 'F'); -- false
select has_ancestor('main', 'E');    -- true
select has_ancestor('G', 'main');    -- true

LAST_INSERT_UUID()

The last_insert_uuid() function returns the UUID of the first row inserted by the last statement executed in the current session. This is the UUID analogue of MySQL's LAST_INSERT_ID() function. We recommend using UUIDs in keys instead of auto_increment values due to their better support for merging values across distributed clones of your database.

While last_insert_id() uses the presence of the auto_increment modifier on a column to determine which automatically generated key value to return, last_insert_uuid() instead depends on the column having a specific definition. For last_insert_uuid() to grab an inserted UUID value, the column must be part of the table's primary key, and it must have one of the following type definitions:

• VARCHAR(36) or CHAR(36) with a default value expression of (UUID())

• VARBINARY(16) or BINARY(16) with a default value expression of (UUID_TO_BIN(UUID()))

When the column is defined as VARBINARY or BINARY and uses the UUID_TO_BIN() function in the default value expression, the swap_flag for UUID_TO_BIN may optionally be specified.

The following code shows how to create a table that conforms to the requirements above and demonstrates how to use last_insert_uuid():

> create table t (pk binary(16) primary key default (UUID_to_bin(UUID())), c1 varchar(100));

> insert into t (c1) values ("one"), ("two");
Query OK, 2 rows affected (0.00 sec)

> select last_insert_uuid();
+--------------------------------------+
| last_insert_uuid()                   |
+--------------------------------------+
| 6cd58555-bb3f-45d8-9302-d32d94d8e28a |
+--------------------------------------+

> select c1 from t where pk = uuid_to_bin(last_insert_uuid());
+-----+
| c1  |
+-----+
| one |
+-----+

Table Functions

Table functions operate like regular SQL functions, but instead of returning a single, scalar value, a table function returns rows of data, just like a table. Dolt's table functions have several restrictions in how they can be used in queries. For example, you cannot currently alias a table function or join a table function with another table or table function.

DOLT_DIFF()

The DOLT_DIFF() table function calculates the differences in a table's data at any two commits in the database. Each row in the result set describes how a row in the underlying table has changed between the two commits, including the row's values at to and from commits and the type of change (i.e. added, modified, or removed). DOLT_DIFF() is an alternative to the dolt_commit_diff_$tablename system table. You should generally prefer the system tables when possible, since they have less restrictions on use. However, some use cases, such as viewing a table data diff containing schema changes or viewing the three dot diff, can be easier to view with the DOLT_DIFF table function.

The main difference between the results of the DOLT_DIFF() table function and the dolt_commit_diff_$tablename system table is the schema of the returned results. dolt_commit_diff_$tablename generates the resulting schema based on the table's schema at the currently checked out branch. DOLT_DIFF() will use the schema at the from_commit for the from_ columns and the schema at the to_commit for the to_ columns. This can make it easier to view diffs where the schema of the underlying table has changed.

Note that the DOLT_DIFF() table function currently has restrictions on how it can be used in queries. It does not support aliasing or joining with other tables, and argument values must currently be literal values.

Options

DOLT_DIFF(<from_revision>, <to_revision>, <tablename>)
DOLT_DIFF(<from_revision..to_revision>, <tablename>)
DOLT_DIFF(<from_revision...to_revision>, <tablename>)

The DOLT_DIFF() table function takes either two or three required arguments:

• from_revision — the revision of the table data for the start of the diff. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~").

• to_revision — the revision of the table data for the end of the diff. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~").

• from_revision..to_revision — gets the two dot diff, or revision of table data between the from_revision and to_revision. This is equivalent to dolt_diff(<from_revision>, <to_revision>, <tablename>).

• from_revision...to_revision — gets the three dot diff, or revision of table data between the from_revision and to_revision, starting at the last common commit.

• tablename — the name of the table containing the data to diff.

Schema

+------------------+----------+
| field            | type     |
+------------------+----------+
| from_commit      | TEXT     |
| from_commit_date | DATETIME |
| to_commit        | TEXT     |
| to_commit_date   | DATETIME |
| diff_type        | TEXT     |
| other cols       |          |
+------------------+----------+

The remaining columns are dependent on the schema of the user table as it existed at the from_commit and at the to_commit. For every column X in your table at the from_commit revision, there is a column in the result set named from_X. Likewise, for every column Y in your table at the to_commit revision, there is a column in the result set named to_Y. This is the major difference between the DOLT_DIFF() table function and the dolt_commit_diff_$tablename system table – DOLT_DIFF() uses the two schemas at the to_commit and from_commit revisions to form the to and from columns of the result set, while dolt_commit_diff_$tablename uses only the table schema of the currently checked out branch to form the to and from columns of the result set.

Example

Consider a table named inventory in a database with two branches: main and feature_branch. We can use the DOLT_DIFF() function to calculate a diff of the table data from the main branch to the feature_branch branch to see how our data has changed on the feature branch.

Here is the schema of inventory at the tip of main:

+----------+------+
| field    | type |
+----------+------+
| pk       | int  |
| name     | text |
| quantity | int  |
+----------+------+

Here is the schema of inventory at the tip of feature_branch:

+----------+------+
| field    | type |
+----------+------+
| pk       | int  |
| name     | text |
| color    | text |
| size     | int  |
+----------+------+

Based on the schemas at the two revision above, the resulting schema from DOLT_DIFF() will be:

+------------------+----------+
| field            | type     |
+------------------+----------+
| from_pk          | int      |
| from_name        | text     |
| from_quantity    | int      |
| from_commit      | TEXT     |
| from_commit_date | DATETIME |
| to_pk            | int      |
| to_name          | text     |
| to_color         | text     |
| to_size          | int      |
| to_commit        | TEXT     |
| to_commit_date   | DATETIME |
| diff_type        | text     |
+------------------+----------+

To calculate the diff and view the results, we run the following query:

SELECT * FROM DOLT_DIFF("main", "feature_branch", "inventory")

The results from DOLT_DIFF() show how the data has changed going from main to feature_branch:

+---------+-------+---------+----------+----------------+-----------------------------------+-----------+---------+---------------+-------------+-----------------------------------+-----------+
| to_name | to_pk | to_size | to_color | to_commit      | to_commit_date                    | from_name | from_pk | from_quantity | from_commit | from_commit_date                  | diff_type |
+---------+-------+---------+----------+----------------+-----------------------------------+-----------+---------+---------------+-------------+-----------------------------------+-----------+
| shirt   | 1     | 15      | false    | feature_branch | 2022-03-23 18:57:38.476 +0000 UTC | shirt     | 1       | 70            | main        | 2022-03-23 18:51:48.333 +0000 UTC | modified  |
| shoes   | 2     | 9       | brown    | feature_branch | 2022-03-23 18:57:38.476 +0000 UTC | shoes     | 2       | 200           | main        | 2022-03-23 18:51:48.333 +0000 UTC | modified  |
| pants   | 3     | 30      | blue     | feature_branch | 2022-03-23 18:57:38.476 +0000 UTC | pants     | 3       | 150           | main        | 2022-03-23 18:51:48.333 +0000 UTC | modified  |
| hat     | 4     | 6       | grey     | feature_branch | 2022-03-23 18:57:38.476 +0000 UTC | NULL      | NULL    | NULL          | main        | 2022-03-23 18:51:48.333 +0000 UTC | added     |
+---------+-------+---------+----------+----------------+-----------------------------------+-----------+---------+---------------+-------------+-----------------------------------+-----------+

Three dot DOLT_DIFF

Let's say the above database has a commit graph that looks like this:

A - B - C - D (main)
         \
          E - F (feature_branch)

The example above gets the two dot diff, or differences between two revisions: main and feature_branch. dolt_diff('main', 'feature_branch', 'inventory') (equivalent to dolt_diff('main..feature_branch', 'inventory')) outputs the difference from F to D (i.e. with effects of E and F).

Three dot diff is useful for showing differences introduced by a feature branch from the point at which it diverged from the main branch. Three dot diff is used to show pull request diffs.

Therefore, dolt_diff('main...feature_branch') outputs just the differences in feature_branch (i.e. E and F).

Learn more about two vs three dot diff here.

DOLT_DIFF_STAT()

Previously dolt_diff_summary()

The DOLT_DIFF_STAT() table function calculates the data difference stat between any two commits in the database. Schema changes such as creating a new table with no rows, or deleting a table with no rows will return empty result. Each row in the result set describes a diff stat for a single table with statistics information of number of rows unmodified, added, deleted and modified, number of cells added, deleted and modified and total number of rows and cells the table has at each commit.

DOLT_DIFF_STAT() works like CLI dolt diff --stat command, but two commits are required to use the DOLT_DIFF_STAT() table function and the table name is optional. For keyless tables, this table function only provides the number of added and deleted rows. It returns empty result for tables with no data changes.

Note that the DOLT_DIFF_STAT() table function currently has restrictions on how it can be used in queries. It does not support aliasing or joining with other tables, and argument values must be literal values.

Privileges

DOLT_DIFF_STAT() table function requires SELECT privilege for all tables if no table is defined or for the defined table only.

Options

DOLT_DIFF_STAT(<from_revision>, <to_revision>, <optional_tablename>)
DOLT_DIFF_STAT(<from_revision..to_revision>, <optional_tablename>)
DOLT_DIFF_STAT(<from_revision...to_revision>, <optional_tablename>)

The DOLT_DIFF_STAT() table function takes three arguments:

• from_revision — the revision of the table data for the start of the diff. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• to_revision — the revision of the table data for the end of the diff. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• from_revision..to_revision — gets the two dot diff stat, or revision of table data between the from_revision and to_revision. This is equivalent to dolt_diff_stat(<from_revision>, <to_revision>, <tablename>).

• from_revision...to_revision — gets the three dot diff stat, or revision of table data between the from_revision and to_revision, starting at the last common commit.

• tablename — the name of the table containing the data to diff. This argument is optional. When it's not defined, all tables with data diff will be returned.

Schema

+-----------------+--------+
| field           | type   |
+-----------------+--------+
| table_name      | TEXT   |
| rows_unmodified | BIGINT |
| rows_added      | BIGINT |
| rows_deleted    | BIGINT |
| rows_modified   | BIGINT |
| cells_added     | BIGINT |
| cells_deleted   | BIGINT |
| cells_modified  | BIGINT |
| old_row_count   | BIGINT |
| new_row_count   | BIGINT |
| old_cell_count  | BIGINT |
| new_cell_count  | BIGINT |
+-----------------+--------+

Example

Consider we start with a table inventory in a database on main branch. When we make any changes, we can use the DOLT_DIFF_STAT() function to calculate a diff of the table data or all tables with data changes across specific commits.

Here is the schema of inventory at the tip of main:

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| pk       | int         | NO   | PRI | NULL    |       |
| name     | varchar(50) | YES  |     | NULL    |       |
| quantity | int         | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+

Here is what table inventory has at the tip of main:

+----+-------+----------+
| pk | name  | quantity |
+----+-------+----------+
| 1  | shirt | 15       |
| 2  | shoes | 10       |
+----+-------+----------+

We perform some changes to the inventory table and create new keyless table:

ALTER TABLE inventory ADD COLUMN color VARCHAR(10);
INSERT INTO inventory VALUES (3, 'hat', 6, 'red');
UPDATE inventory SET quantity=0 WHERE pk=1;
CREATE TABLE items (name varchar(50));
INSERT INTO items VALUES ('shirt'),('pants');

Here is what table inventory has in the current working set:

+----+-------+----------+-------+
| pk | name  | quantity | color |
+----+-------+----------+-------+
| 1  | shirt | 0        | NULL  |
| 2  | shoes | 10       | NULL  |
| 3  | hat   | 6        | red   |
+----+-------+----------+-------+

To calculate the diff and view the results, we run the following query:

SELECT * FROM DOLT_DIFF_STAT('main', 'WORKING');

The results from DOLT_DIFF_STAT() show how the data has changed going from tip of main to our current working set:

+------------+-----------------+------------+--------------+---------------+-------------+---------------+----------------+---------------+---------------+----------------+----------------+
| table_name | rows_unmodified | rows_added | rows_deleted | rows_modified | cells_added | cells_deleted | cells_modified | old_row_count | new_row_count | old_cell_count | new_cell_count |
+------------+-----------------+------------+--------------+---------------+-------------+---------------+----------------+---------------+---------------+----------------+----------------+
| inventory  | 1               | 1          | 0            | 1             | 6           | 0             | 1              | 2             | 3             | 6              | 12             |
| items      | NULL            | 2          | 0            | NULL          | NULL        | NULL          | NULL           | NULL          | NULL          | NULL           | NULL           |
+------------+-----------------+------------+--------------+---------------+-------------+---------------+----------------+---------------+---------------+----------------+----------------+

To get a table specific changes going from the current working set to tip of main, we run the following query:

SELECT * FROM DOLT_DIFF_STAT('WORKING', 'main', 'inventory');

With result of single row:

+------------+-----------------+------------+--------------+---------------+-------------+---------------+----------------+---------------+---------------+----------------+----------------+
| table_name | rows_unmodified | rows_added | rows_deleted | rows_modified | cells_added | cells_deleted | cells_modified | old_row_count | new_row_count | old_cell_count | new_cell_count |
+------------+-----------------+------------+--------------+---------------+-------------+---------------+----------------+---------------+---------------+----------------+----------------+
| inventory  | 1               | 0          | 1            | 1             | 0           | 6             | 1              | 3             | 2             | 12             | 6              |
+------------+-----------------+------------+--------------+---------------+-------------+---------------+----------------+---------------+---------------+----------------+----------------+

DOLT_DIFF_SUMMARY()

The previous version of dolt_diff_summary was renamed to dolt_diff_stat.

The DOLT_DIFF_SUMMARY() table function is a summary of what tables changed and how between any two commits in the database. Only changed tables will be listed in the result, along with the diff type ('added', 'dropped', 'modified', 'renamed') and whether there are data and schema changes.

DOLT_DIFF_SUMMARY() works like CLI dolt diff --summary command, but two commits are required to use the DOLT_DIFF_SUMMARY() table function and the table name is optional. It returns empty result if there are no tables with changes.

Note that the DOLT_DIFF_SUMMARY() table function currently has restrictions on how it can be used in queries. It does not support aliasing or joining with other tables, and argument values must be literal values.

Privileges

DOLT_DIFF_SUMMARY() table function requires SELECT privilege for all tables if no table is defined or for the defined table only.

Options

DOLT_DIFF_SUMMARY(<from_revision>, <to_revision>, <optional_tablename>)
DOLT_DIFF_SUMMARY(<from_revision..to_revision>, <optional_tablename>)
DOLT_DIFF_SUMMARY(<from_revision...to_revision>, <optional_tablename>)

The DOLT_DIFF_SUMMARY() table function takes three arguments:

• from_revision — the revision of the table data for the start of the diff. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• to_revision — the revision of the table data for the end of the diff. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• from_revision..to_revision — gets the two dot diff summary, or revision of table data between the from_revision and to_revision. This is equivalent to dolt_diff_summary(<from_revision>, <to_revision>, <tablename>).

• from_revision...to_revision — gets the three dot diff summary, or revision of table data between the from_revision and to_revision, starting at the last common commit.

• tablename — the name of the table containing the data to diff. This argument is optional. When it's not defined, all tables with data diff will be returned.

Schema

+-----------------+---------+
| field           | type    |
+-----------------+---------+
| from_table_name | TEXT    |
| to_table_name   | TEXT    |
| diff_type       | TEXT    |
| data_change     | BOOLEAN |
| schema_change   | BOOLEAN |
+-----------------+---------+

Example

Consider we start with a table inventory in a database on main branch. When we make any changes, we can use the DOLT_DIFF_SUMMARY() function to calculate a diff of the table data or all tables with data changes across specific commits.

Here is the schema of inventory at the tip of main:

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| pk       | int         | NO   | PRI | NULL    |       |
| name     | varchar(50) | YES  |     | NULL    |       |
| quantity | int         | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+

Here is what table inventory has at the tip of main:

+----+-------+----------+
| pk | name  | quantity |
+----+-------+----------+
| 1  | shirt | 15       |
| 2  | shoes | 10       |
+----+-------+----------+

We perform some changes to the inventory table and create new keyless table:

ALTER TABLE inventory ADD COLUMN color VARCHAR(10);
INSERT INTO inventory VALUES (3, 'hat', 6, 'red');
UPDATE inventory SET quantity=0 WHERE pk=1;
CREATE TABLE items (name varchar(50));

Here is what table inventory has in the current working set:

+----+-------+----------+-------+
| pk | name  | quantity | color |
+----+-------+----------+-------+
| 1  | shirt | 0        | NULL  |
| 2  | shoes | 10       | NULL  |
| 3  | hat   | 6        | red   |
+----+-------+----------+-------+

To calculate the diff and view the results, we run the following query:

SELECT * FROM DOLT_DIFF_SUMMARY('main', 'WORKING');

The results from DOLT_DIFF_SUMMARY() show how the data has changed going from tip of main to our current working set:

+-----------------+---------------+-----------+-------------+---------------+
| from_table_name | to_table_name | diff_type | data_change | schema_change |
+-----------------+---------------+-----------+-------------+---------------+
| inventory       | inventory     | modified  | true        | true          |
| items           | items         | added     | false       | true          |
+-----------------+---------------+-----------+-------------+---------------+

To get a table specific changes going from the current working set to tip of main, we run the following query:

SELECT * FROM DOLT_DIFF_SUMMARY('WORKING', 'main', 'inventory');

With result of single row:

+-----------------+---------------+-----------+-------------+---------------+
| from_table_name | to_table_name | diff_type | data_change | schema_change |
+-----------------+---------------+-----------+-------------+---------------+
| inventory       | inventory     | modified  | true        | true          |
+-----------------+---------------+-----------+-------------+---------------+

DOLT_LOG()

The DOLT_LOG table function gets the commit log for all commits reachable from the provided revision's HEAD (or the current HEAD if no revision is provided). DOLT_LOG() works like CLI dolt log command.

Note that the DOLT_LOG() table function currently has restrictions on how it can be used in queries. It does not support aliasing or joining with other tables, and argument values must be literal values.

Privileges

DOLT_LOG() table function requires SELECT privilege for all tables.

Options

DOLT_LOG([<optional_revisions>...], [--tables <tables>...])

The DOLT_LOG() table function takes any number of optional revision arguments:

• optional_revision: a branch name, tag, or commit ref (with or without an ancestor spec) that specifies which ancestor commits to include in the results. If no revisions are specified, the default is the current branch HEAD.

  • If you'd like to get two dot logs (all commits reachable by revision2, but NOT reachable by revision1), you can use .. between revisions (DOLT_LOG('revision1..revision2')) or ^ in front of the revision you'd like to exclude (DOLT_LOG('revision2', '^revision1')). Note: if providing two revisions, one must contain ^.

  • If you'd like to get three dot logs (all commits reachable by revision1 or revision2, excluding commits reachable by BOTH revision1 AND revision2), you can use ... between revisions (DOLT_LOG('revision1...revision2').

• --min-parents: The minimum number of parents a commit must have to be included in the log.

• --merges: Equivalent to min-parents == 2, this will limit the log to commits with 2 or more parents.

• --parents: Shows all parents of each commit in the log.

• --decorate: Shows refs next to commits. Valid options are short, full, no, and auto. Note: the CLI dolt log command defaults to "short", while this table function defaults to "no".

• --not: Excludes commits reachable by revision.

• --tables: Limits the log to commits that affect the specified tables. Any number of comma separated tables can be specified.

Schema

+-------------+----------+
| field       | type     |
+-------------+--------- +
| commit_hash | text     |
| committer   | text     |
| email       | text     |
| date        | datetime |
| message     | text     |
| parents     | text     | -- column hidden unless `--parents` flag provided
| refs        | text     | -- column hidden unless `--decorate` is "short" or "full"
+-------------+--------- +

Example

Consider we have the following commit graph:

A - B - C - D (main)
         \
          E - F (feature)

To get the commit log for the main branch, we can use the query:

SELECT * FROM DOLT_LOG('main');

And it would return commits in reverse-chronological order - D,C, B, and A. The output will look something like:

+----------------------------------+-----------+--------------------+-----------------------------------+---------------+
| commit_hash                      | committer | email              | date                              | message       |
+----------------------------------+-----------+--------------------+-----------------------------------+---------------+
| qi331vjgoavqpi5am334cji1gmhlkdv5 | bheni     | [e-mail] | 2019-06-07 00:22:24.856 +0000 UTC | update rating  |
| 137qgvrsve1u458briekqar5f7iiqq2j | bheni     | [e-mail] | 2019-04-04 22:43:00.197 +0000 UTC | change rating  |
| rqpd7ga1nic3jmc54h44qa05i8124vsp | bheni     | [e-mail] | 2019-04-04 21:07:36.536 +0000 UTC | fixes          |
| qfk3bpan8mtrl05n8nihh2e3t68t3hrk | bheni     | [e-mail] | 2019-04-04 21:01:16.649 +0000 UTC | test           |
+----------------------------------+-----------+--------------------+-----------------------------------+---------------+

To get the commit log for the feature branch, we can change the revision in the above query:

SELECT * FROM DOLT_LOG('feature');

And it would return all commits reachable from the HEAD of feature - F, E, C, B, and A.

Two and three dot log

We also support two and three dot log. Two dot log returns commits from a revision, excluding commits from another revision. If we want all commits in feature, excluding commits from main, all of these queries will return commits F and E.

SELECT * FROM DOLT_LOG('main..feature');
SELECT * FROM DOLT_LOG('feature', '^main');
SELECT * FROM DOLT_LOG('feature', '--not', 'main');

Three dot log returns commits in either revision, excluding commits in BOTH revisions. If we want commits in main OR feature, excluding commits in main AND feature, this query would return commits F, E, and D.

SELECT * FROM DOLT_LOG('main...feature');

Note: The order of revisions in two dot log matters, but not for three dot log. DOLT_LOG('main..feature') returns F and E, while DOLT_LOG('feature..main') returns just D. DOLT_LOG('main...feature') and DOLT_LOG('feature...main') both return F, E, and D.

Learn more about two vs three dot log here.

DOLT_PATCH()

Generate the SQL statements needed to patch a table (or all tables) from a starting revision to a target revision. This can be useful when you want to import data into Dolt from an external source, compare differences, and generate the SQL statements needed to patch the original source. This command is equivalent of dolt diff -r sql CLI command. Both schema and/or data diff statements are returned if applicable. Some data diff cannot be produced from incompatible schema changes; these are shown as warnings containing which table this occurred on.

The order of the statements is that the schema patch comes first after the data patch. If patching all tables, then we recommend to turn off the foreign key checks (SET foreign_key_checks=0;) before applying these patch statements in order of them returned to avoid conflicts.

Getting SQL patch statements is only available as table function for now; the CLI dolt patch command will be supported in the future.

Privileges

DOLT_PATCH() table function requires SELECT privilege for all tables if no table is defined or for the defined table only.

Options

DOLT_PATCH(<from_revision>, <to_revision>, <optional_tablename>)
DOLT_PATCH(<from_revision..to_revision>, <optional_tablename>)
DOLT_PATCH(<from_revision...to_revision>, <optional_tablename>)

The DOLT_PATCH() table function takes the following arguments:

• from_revision — the revision of the table data for the start of the patch. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• to_revision — the revision of the table data for the end of the patch. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• from_revision..to_revision — gets the two dot patch, or revision of table data between the from_revision and to_revision. This is equivalent to dolt_patch(<from_revision>, <to_revision>, <tablename>).

• from_revision...to_revision — gets the three dot patch, or revision of table data between the from_revision and to_revision, starting at the last common commit.

• tablename — the name of the table containing the data and/or schema to patch. This argument is optional. When it's not defined, all tables with data and/or schema patch will be returned.

Schema

+------------------+--------+
| field            | type   |
+------------------+--------+
| statement_order  | BIGINT |
| from_commit_hash | TEXT   |
| to_commit_hash   | TEXT   |
| table_name       | TEXT   |
| diff_type        | TEXT   |
| statement        | TEXT   |
+------------------+--------+

Example

Consider we start with a table inventory in a database on main branch. When we make any changes, we can use the DOLT_PATCH() function to get SQL patch statements of the table data or all tables with data changes across specific commits.

Here is the schema of inventory at the tip of main:

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| pk       | int         | NO   | PRI | NULL    |       |
| name     | varchar(50) | YES  |     | NULL    |       |
| quantity | int         | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+

Here is what table inventory has at the tip of main:

+----+-------+----------+
| pk | name  | quantity |
+----+-------+----------+
| 1  | shirt | 15       |
| 2  | shoes | 10       |
+----+-------+----------+

We perform some changes to the inventory table and create new keyless table:

INSERT INTO inventory VALUES (3, 'hat', 6);
UPDATE inventory SET quantity=0 WHERE pk=1;
CREATE TABLE items (name varchar(50));
INSERT INTO items VALUES ('shirt'),('pants');

Here is what table inventory has in the current working set:

+----+-------+----------+
| pk | name  | quantity |
+----+-------+----------+
| 1  | shirt | 0        |
| 2  | shoes | 10       |
| 3  | hat   | 6        |
+----+-------+----------+

To get SQL patch statements, we run the following query:

SELECT * FROM DOLT_PATCH('main', 'WORKING');

The results from DOLT_PATCH() show how the data has changed going from tip of main to our current working set:

+-----------------+----------------------------------+----------------+------------+-----------+----------------------------------------------------------------------+
| statement_order | from_commit_hash                 | to_commit_hash | table_name | diff_type | statement                                                            |
+-----------------+----------------------------------+----------------+------------+-----------+----------------------------------------------------------------------+
| 1               | gg4kasjl6tgrtoag8tnn1der09sit4co | WORKING        | inventory  | data      | UPDATE `inventory` SET `quantity`=0 WHERE `pk`=1;                    |
| 2               | gg4kasjl6tgrtoag8tnn1der09sit4co | WORKING        | inventory  | data      | INSERT INTO `inventory` (`pk`,`name`,`quantity`) VALUES (3,'hat',6); |
| 3               | gg4kasjl6tgrtoag8tnn1der09sit4co | WORKING        | items      | schema    | CREATE TABLE `items` (                                               |
|                 |                                  |                |            |           |   `name` varchar(50)                                                 |
|                 |                                  |                |            |           | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin;    |
| 4               | gg4kasjl6tgrtoag8tnn1der09sit4co | WORKING        | items      | data      | INSERT INTO `items` (`name`) VALUES ('shirt');                       |
| 5               | gg4kasjl6tgrtoag8tnn1der09sit4co | WORKING        | items      | data      | INSERT INTO `items` (`name`) VALUES ('pants');                       |
+-----------------+----------------------------------+----------------+------------+-----------+----------------------------------------------------------------------+

To get a table specific schema patch going from the current working set to tip of main, we run the following query:

SELECT * FROM DOLT_PATCH('WORKING', 'main', 'items') WHERE diff_type = 'schema';

With result of single row:

+-----------------+------------------+----------------------------------+------------+-----------+---------------------+
| statement_order | from_commit_hash | to_commit_hash                   | table_name | diff_type | statement           |
+-----------------+------------------+----------------------------------+------------+-----------+---------------------+
| 1               | WORKING          | gg4kasjl6tgrtoag8tnn1der09sit4co | items      | schema    | DROP TABLE `items`; |
+-----------------+------------------+----------------------------------+------------+-----------+---------------------+

DOLT_REFLOG()

The DOLT_REFLOG() table function shows the history of named refs (e.g. branches and tags), which is useful when you want to understand how a branch or tag has changed over time to reference different commits, particularly for information that isn't surfaced through the dolt_log system table or dolt_log() table function. For example, if you use dolt_reset() to change the commit a branch points to, you can use dolt_reflog() to see what commit the branch was pointing to before it was moved to that commit. Another common use case for dolt_reflog() is to recreate a branch or tag that was accidentally deleted. The example section below shows how to recreate a deleted branch.

The data from Dolt's reflog comes from Dolt's journaling chunk store. This data is local to a Dolt database and never included when pushing, pulling, or cloning a Dolt database. This means when you clone a Dolt database, it will not have any reflog data until you perform operations that change what commit branches or tags reference.

Dolt's reflog is similar to Git's reflog, but there are a few differences:

• The Dolt reflog currently only supports named references, such as branches and tags, and not any of Git's special refs (e.g. HEAD, FETCH-HEAD, MERGE-HEAD).

• The Dolt reflog can be queried for the log of references, even after a reference has been deleted. In Git, once a branch or tag is deleted, the reflog for that ref is also deleted and to find the last commit a branch or tag pointed to you have to use Git's special HEAD reflog to find the commit, which can sometimes be challenging. Dolt makes this much easier by allowing you to see the history for a deleted ref so you can easily see the last commit a branch or tag pointed to before it was deleted.

Privileges

There are no special privileges required to use the dolt_reflog() table function.

Options

DOLT_REFLOG()
DOLT_REFLOG(['--all'], <ref_name>)

The dolt_reflog() table function can be called with no arguments or with one argument. If called without any arguments, it will return the full reference log, which lists changes from newest to oldest for all tracked references. If called with one argument, that argument is the name of a ref to query. This can be the name of a branch (e.g. "myBranch") or the name of a tag (e.g. "v1.1.4") or it can be the fully qualified ref path (e.g. "refs/heads/myBranch"). The ref_name parameter is case-insensitive.

The dolt_reflog() table function can also be called with the --all flag to show all refs, including hidden refs, such as DoltHub workspace refs.

Schema

+-----------------------+-----------+
| field                 | type      |
+-----------------------+-----------+
| ref                   | TEXT      |
| ref_timestamp         | TIMESTAMP |
| commit_hash           | TEXT      |
| commit_message        | TEXT      |
+-----------------------+-----------+

Example

The example below shows how to recreate a branch that was deleted by finding the last commit it referenced in Dolt's reflog.

-- Someone accidentally deletes the wrong branch!
call dolt_branch('-D', 'prodBranch');

-- After we realize the wrong branch has been deleted, we query the Dolt reflog on the same Dolt database instance
-- where the branch was deleted to see what commits the prodBranch branch has referenced. Using the same Dolt 
-- instance is important, since reflog information is always local and not included when pushing/pulling databases.
select * from dolt_reflog('prodBranch');
+-----------------------+---------------------+----------------------------------+-------------------------------+
| ref                   | ref_timestamp       | commit_hash                      | commit_message                |
+-----------------------+---------------------+----------------------------------+-------------------------------+
| refs/heads/prodBranch | 2023-10-25 20:54:37 | v531ptpmv2tquig8v591tsjghtj84ksg | inserting row 42              |
| refs/heads/prodBranch | 2023-10-25 20:53:12 | rvt34lqrbtdr3dhnjchruu73lik4e398 | inserting row 100000          |
| refs/heads/prodBranch | 2023-10-25 20:53:06 | v531ptpmv2tquig8v591tsjghtj84ksg | inserting row 42              |
| refs/heads/prodBranch | 2023-10-25 20:52:43 | ihuj1l7fmqq37sjhtlrgpup5n76gfhju | inserting row 1 into table xy |
+-----------------------+---------------------+----------------------------------+-------------------------------+

-- The last commit prodBranch pointed to was v531ptpmv2tquig8v591tsjghtj84ksg, so to restore our branch, we
-- just need to create a branch with the same name, pointing to that last commit.
call dolt_branch('prodBranch', 'v531ptpmv2tquig8v591tsjghtj84ksg');

DOLT_SCHEMA_DIFF()

The DOLT_SCHEMA_DIFF() table function calculates the schema difference between any two commits in the database. Each row in the result set describes how a table was altered between the two commits, including the table's create statement at to and from commits.

Note that the DOLT_SCHEMA_DIFF() table function currently has restrictions on how it can be used in queries. It does not support aliasing or joining with other tables, and argument values must currently be literal values.

Privileges

DOLT_SCHEMA_DIFF() table function requires SELECT privilege for all tables if no table is defined or for the defined table only.

Options

DOLT_SCHEMA_DIFF(<from_commit>, <to_commit>, <optional_tablename>)
DOLT_SCHEMA_DIFF(<from_revision..to_revision>, <optional_tablename>)
DOLT_SCHEMA_DIFF(<from_revision...to_revision>, <optional_tablename>)

The DOLT_SCHEMA_DIFF() table function takes three arguments:

• from_revision — the revision of the table data for the start of the diff. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• to_revision — the revision of the table data for the end of the diff. This argument is required. This may be a commit, tag, branch name, or other revision specifier (e.g. "main~", "WORKING", "STAGED").

• from_revision..to_revision — gets the two dot diff, or revision of table schema between the from_revision and to_revision. This is equivalent to dolt_schema_diff(<from_revision>, <to_revision>, [<tablename>]).

• from_revision...to_revision — gets the three dot diff, or revision of table schema between the from_revision and to_revision, starting at the last common commit.

• tablename — the name of the table to diff. This argument is optional. When it's not defined, all tables with schema diffs will be returned.

Schema

+-----------------------+------+
| field                 | type |
+-----------------------+------+
| from_table_name       | TEXT |
| to_table_name         | TEXT |
| from_create_statement | TEXT |
| to_create_statement   | TEXT |
+-----------------------+------+

Example

For this example, we'll consider three tables within the context of two branches: main and feature_branch.

These are the tables on main: employees, inventory, vacations. These are the tables on feature_branch: inventory, photos, trips.

To figure out how these tables changed, we run the following query:

SELECT * FROM DOLT_SCHEMA_DIFF("main", "feature_branch")

The results from DOLT_SCHEMA_DIFF() show how the schema for all tables has changed going from tip of main to tip of feature_branch:

+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| from_table_name | to_table_name | from_create_statement                                             | to_create_statement                                               |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| employees       |               | CREATE TABLE `employees` (                                        |                                                                   |
|                 |               |   `pk` int NOT NULL,                                              |                                                                   |
|                 |               |   `name` varchar(50),                                             |                                                                   |
|                 |               |   PRIMARY KEY (`pk`)                                              |                                                                   |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |                                                                   |
| inventory       | inventory     | CREATE TABLE `inventory` (                                        | CREATE TABLE `inventory` (                                        |
|                 |               |   `pk` int NOT NULL,                                              |   `pk` int NOT NULL,                                              |
|                 |               |   `name` varchar(50),                                             |   `name` varchar(50),                                             |
|                 |               |   `quantity` int,                                                 |   `color` varchar(10),                                            |
|                 |               |   PRIMARY KEY (`pk`)                                              |   PRIMARY KEY (`pk`)                                              |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
|                 | photos        |                                                                   | CREATE TABLE `photos` (                                           |
|                 |               |                                                                   |   `pk` int NOT NULL,                                              |
|                 |               |                                                                   |   `name` varchar(50),                                             |
|                 |               |                                                                   |   `dt` datetime(6),                                               |
|                 |               |                                                                   |   PRIMARY KEY (`pk`)                                              |
|                 |               |                                                                   | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
| vacations       | trips         | CREATE TABLE `vacations` (                                        | CREATE TABLE `trips` (                                            |
|                 |               |   `pk` int NOT NULL,                                              |   `pk` int NOT NULL,                                              |
|                 |               |   `name` varchar(50),                                             |   `name` varchar(50),                                             |
|                 |               |   PRIMARY KEY (`pk`)                                              |   PRIMARY KEY (`pk`)                                              |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+

Let's look at the returned data.

1. The first row has values in from_table_name and from_create_statement columns, while to_table_name and to_create_statement columns are empty. This means that between main and feature_branch, the table employees was deleted.

2. The second row has identical values for from_table_name and to_table_name, but from_create_statement is different from to_create_statement. This means the table's schema changed between main and feature_branch.

3. The third row is similar to the first row, except its to_* columns are empty, and from_* columns are set. This means that between main and feature_branch, the table photos was added.

4. Finally, the last row has mostly identical from_create_statement and to_create_statement columns, but different from_table_name and to_table_name columns. This means the table was renamed changed between main and feature_branch.

We invoked DOLT_SCHEMA_DIFF() with branch names, but we could have used any revision specifier. For example, we could have used commit hashes or tag names, and would have gotten the same results.

Using tags or commit hashes:

select * from dolt_schema_diff('v1', 'v1.1');
select * from dolt_schema_diff('tjj1kp2mnoad8crv6b94mh4a4jiq7ab2', 'v391rm7r0t4989sgomv0rpn9ue4ugo6g');

So far, we have always supplied just the first two parameters, the from and to revisions, but we have not specified the optional table parameter, so DOLT_SCHEMA_DIFF() returned schema diffs of all changed tables. We can scope DOLT_SCHEMA_DIFF() to a specific table simply by specifying it as the last parameter.

Let's try this with the inventory table.

SELECT * FROM DOLT_SCHEMA_DIFF("main", "feature_branch", "inventory")

We will see this set of results:

+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| from_table_name | to_table_name | from_create_statement                                             | to_create_statement                                               |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| inventory       | inventory     | CREATE TABLE `inventory` (                                        | CREATE TABLE `inventory` (                                        |
|                 |               |   `pk` int NOT NULL,                                              |   `pk` int NOT NULL,                                              |
|                 |               |   `name` varchar(50),                                             |   `name` varchar(50),                                             |
|                 |               |   `quantity` int,                                                 |   `color` varchar(10),                                            |
|                 |               |   PRIMARY KEY (`pk`)                                              |   PRIMARY KEY (`pk`)                                              |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+

When a table is renamed, we can specify either the "old" table name, or the "new" table name, and we will receive the same results. The following two queries will provide the same results:

SELECT * FROM DOLT_SCHEMA_DIFF("main", "feature_branch", "trips");
SELECT * FROM DOLT_SCHEMA_DIFF("main", "feature_branch", "vacations");

Here are the results:

+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| from_table_name | to_table_name | from_create_statement                                             | to_create_statement                                               |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| vacations       | trips         | CREATE TABLE `vacations` (                                        | CREATE TABLE `trips` (                                            |
|                 |               |   `pk` int NOT NULL,                                              |   `pk` int NOT NULL,                                              |
|                 |               |   `name` varchar(50),                                             |   `name` varchar(50),                                             |
|                 |               |   PRIMARY KEY (`pk`)                                              |   PRIMARY KEY (`pk`)                                              |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+

Finally, we can flip the order of the revisions to get the schema diff in the opposite direction.

select * from dolt_schema_diff('feature_branch', 'main');

The above query will produce this output:

+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| from_table_name | to_table_name | from_create_statement                                             | to_create_statement                                               |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+
| photos          |               | CREATE TABLE `photos` (                                           |                                                                   |
|                 |               |   `pk` int NOT NULL,                                              |                                                                   |
|                 |               |   `name` varchar(50),                                             |                                                                   |
|                 |               |   `dt` datetime(6),                                               |                                                                   |
|                 |               |   PRIMARY KEY (`pk`)                                              |                                                                   |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |                                                                   |
|                 | employees     |                                                                   | CREATE TABLE `employees` (                                        |
|                 |               |                                                                   |   `pk` int NOT NULL,                                              |
|                 |               |                                                                   |   `name` varchar(50),                                             |
|                 |               |                                                                   |   PRIMARY KEY (`pk`)                                              |
|                 |               |                                                                   | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
| inventory       | inventory     | CREATE TABLE `inventory` (                                        | CREATE TABLE `inventory` (                                        |
|                 |               |   `pk` int NOT NULL,                                              |   `pk` int NOT NULL,                                              |
|                 |               |   `name` varchar(50),                                             |   `name` varchar(50),                                             |
|                 |               |   `color` varchar(10),                                            |   `quantity` int,                                                 |
|                 |               |   PRIMARY KEY (`pk`)                                              |   PRIMARY KEY (`pk`)                                              |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
| trips           | vacations     | CREATE TABLE `trips` (                                            | CREATE TABLE `vacations` (                                        |
|                 |               |   `pk` int NOT NULL,                                              |   `pk` int NOT NULL,                                              |
|                 |               |   `name` varchar(50),                                             |   `name` varchar(50),                                             |
|                 |               |   PRIMARY KEY (`pk`)                                              |   PRIMARY KEY (`pk`)                                              |
|                 |               | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_bin; |
+-----------------+---------------+-------------------------------------------------------------------+-------------------------------------------------------------------+

Note the difference between this call and the previous dolt_schema_diff('main', 'feature_branch') invocation:

1. First row shows that the table photos was deleted

2. Second row show the creation of employees table

3. Third row has the from_create_statement and to_create_statement columns swapped

4. Fourth row shows the inverse rename of trips to vacations

Example query

You can try calling DOLT_SCHEMA_DIFF() against the DoltHub docs_examples DB, by getting the diff of schemas between schema_diff_v1 and schema_diff_v2 tags, which correspond to main and feature_branch branches from these examples.

https://www.dolthub.com/repositories/dolthub/docs_examples/embed/main?active=Tables&q=SELECT+*%0AFROM+dolt_schema_diff%28%27schema_diff_v1%27%2C+%27schema_diff_v2%27%29%3B%0A

DOLT_QUERY_DIFF()

The DOLT_QUERY_DIFF() table function calculates the data difference between any two queries, producing a table similar to the DOLT_DIFF() table function.

Privileges

DOLT_QUERY_DIFF() table function requires SELECT privilege for all tables used in each query.

Example

For this example, we have the table t in two branches main and other.

On main, the table t has the following data:

+---+----+
| i | j  |
+---+----+
| 0 | 0  |
| 1 | 10 |
| 3 | 3  |
| 4 | 4  |
+---+----+

On other, the table t has the following data:

+---+---+
| i | j |
+---+---+
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 4 | 4 |
+---+---+

We can use the DOLT_QUERY_DIFF() table function to calculate the difference between the two tables:

dolt> select * from dolt_query_diff('select * from t as of main', 'select * from t as of other');
+--------+--------+------+------+-----------+
| from_i | from_j | to_i | to_j | diff_type |
+--------+--------+------+------+-----------+
| 1      | 10     | 1    | 1    | modified  |
| NULL   | NULL   | 2    | 2    | added     |
| 3      | 3      | NULL | NULL | deleted   |
+--------+--------+------+------+-----------+
3 rows in set (0.00 sec)

Note

Query diff is performed brute force and thus, will be slow for large result sets. The algorithm is super linear (n^2) on the size of the results sets. Over time, we will optimize this to use features of the storage engine to improve performance.