System Tables #

Table Specified System Table #

Table specified system tables contain metadata and information about each table, such as the snapshots created and the options in use. Users can access system tables with batch queries.

Currently, Flink, Spark, Trino and StarRocks support querying system tables.

In some cases, the table name needs to be enclosed with back quotes to avoid syntax parsing conflicts, for example triple access mode:

SELECT * FROM my_catalog.my_db.`my_table$snapshots`;

Snapshots Table #

You can query the snapshot history information of the table through snapshots table, including the record count occurred in the snapshot.

SELECT * FROM my_table$snapshots;

/*
+--------------+------------+-----------------+-------------------+--------------+-------------------------+--------------------------------+------------------------------- +--------------------------------+---------------------+---------------------+-------------------------+----------------+
|  snapshot_id |  schema_id |     commit_user | commit_identifier |  commit_kind |             commit_time |             base_manifest_list |            delta_manifest_list |        changelog_manifest_list |  total_record_count |  delta_record_count |  changelog_record_count |      watermark |
+--------------+------------+-----------------+-------------------+--------------+-------------------------+--------------------------------+------------------------------- +--------------------------------+---------------------+---------------------+-------------------------+----------------+
|            2 |          0 | 7ca4cd28-98e... |                 2 |       APPEND | 2022-10-26 11:44:15.600 | manifest-list-31323d5f-76e6... | manifest-list-31323d5f-76e6... | manifest-list-31323d5f-76e6... |                   2 |                   2 |                       0 |  1666755855600 |
|            1 |          0 | 870062aa-3e9... |                 1 |       APPEND | 2022-10-26 11:44:15.148 | manifest-list-31593d5f-76e6... | manifest-list-31593d5f-76e6... | manifest-list-31593d5f-76e6... |                   1 |                   1 |                       0 |  1666755855148 |
+--------------+------------+-----------------+-------------------+--------------+-------------------------+--------------------------------+------------------------------- +--------------------------------+---------------------+---------------------+-------------------------+----------------+
2 rows in set
*/

By querying the snapshots table, you can know the commit and expiration information about that table and time travel through the data.

Schemas Table #

You can query the historical schemas of the table through schemas table.

SELECT * FROM my_table$schemas;

/*
+-----------+--------------------------------+----------------+--------------+---------+---------+-------------------------+
| schema_id |                         fields | partition_keys | primary_keys | options | comment |       update_time       |
+-----------+--------------------------------+----------------+--------------+---------+---------+-------------------------+
|         0 | [{"id":0,"name":"word","typ... |             [] |     ["word"] |      {} |         | 2022-10-28 11:44:20.600 |
|         1 | [{"id":0,"name":"word","typ... |             [] |     ["word"] |      {} |         | 2022-10-27 11:44:15.600 |
|         2 | [{"id":0,"name":"word","typ... |             [] |     ["word"] |      {} |         | 2022-10-26 11:44:10.600 |
+-----------+--------------------------------+----------------+--------------+---------+---------+-------------------------+
3 rows in set
*/

You can join the snapshots table and schemas table to get the fields of given snapshots.

SELECT s.snapshot_id, t.schema_id, t.fields 
    FROM my_table$snapshots s JOIN my_table$schemas t 
    ON s.schema_id=t.schema_id where s.snapshot_id=100;

Options Table #

You can query the table’s option information which is specified from the DDL through options table. The options not shown will be the default value. You can take reference to Configuration.

SELECT * FROM my_table$options;

/*
+------------------------+--------------------+
|         key            |        value       |
+------------------------+--------------------+
| snapshot.time-retained |         5 h        |
+------------------------+--------------------+
1 rows in set
*/

Audit log Table #

If you need to audit the changelog of the table, you can use the audit_log system table. Through audit_log table, you can get the rowkind column when you get the incremental data of the table. You can use this column for filtering and other operations to complete the audit.

There are four values for rowkind:

+I: Insertion operation.
-U: Update operation with the previous content of the updated row.
+U: Update operation with new content of the updated row.
-D: Deletion operation.

SELECT * FROM my_table$audit_log;

/*
+------------------+-----------------+-----------------+
|     rowkind      |     column_0    |     column_1    |
+------------------+-----------------+-----------------+
|        +I        |      ...        |      ...        |
+------------------+-----------------+-----------------+
|        -U        |      ...        |      ...        |
+------------------+-----------------+-----------------+
|        +U        |      ...        |      ...        |
+------------------+-----------------+-----------------+
3 rows in set
*/

Read-optimized Table #

If you require extreme reading performance and can accept reading slightly old data, you can use the ro (read-optimized) system table. Read-optimized system table improves reading performance by only scanning files which does not need merging.

For primary-key tables, ro system table only scans files on the topmost level. That is to say, ro system table only produces the result of the latest full compaction.

It is possible that different buckets carry out full compaction at difference times, so it is possible that the values of different keys come from different snapshots.

For append tables, as all files can be read without merging, ro system table acts like the normal append table.

SELECT * FROM my_table$ro;

Files Table #

You can query the files of the table with specific snapshot.

-- Query the files of latest snapshot
SELECT * FROM my_table$files;

/*
+-----------+--------+--------------------------------+-------------+-----------+-------+--------------+--------------------+---------+---------+------------------------+-------------------------+-------------------------+---------------------+---------------------+-----------------------+
| partition | bucket |                      file_path | file_format | schema_id | level | record_count | file_size_in_bytes | min_key | max_key |      null_value_counts |         min_value_stats |         max_value_stats | min_sequence_number | max_sequence_number |         creation_time |
+-----------+--------+--------------------------------+-------------+-----------+-------+--------------+--------------------+---------+---------+------------------------+-------------------------+-------------------------+---------------------+---------------------+-----------------------+
|       [3] |      0 | data-8f64af95-29cc-4342-adc... |         orc |         0 |     0 |            1 |                593 |     [c] |     [c] | {cnt=0, val=0, word=0} | {cnt=3, val=33, word=c} | {cnt=3, val=33, word=c} |       1691551246234 |       1691551246637 |2023-02-24T16:06:21.166|
|       [2] |      0 | data-8b369068-0d37-4011-aa5... |         orc |         0 |     0 |            1 |                593 |     [b] |     [b] | {cnt=0, val=0, word=0} | {cnt=2, val=22, word=b} | {cnt=2, val=22, word=b} |       1691551246233 |       1691551246732 |2023-02-24T16:06:21.166|
|       [2] |      0 | data-83aa7973-060b-40b6-8c8... |         orc |         0 |     0 |            1 |                605 |     [d] |     [d] | {cnt=0, val=0, word=0} | {cnt=2, val=32, word=d} | {cnt=2, val=32, word=d} |       1691551246267 |       1691551246798 |2023-02-24T16:06:21.166|
|       [5] |      0 | data-3d304f4a-bcea-44dc-a13... |         orc |         0 |     0 |            1 |                593 |     [c] |     [c] | {cnt=0, val=0, word=0} | {cnt=5, val=51, word=c} | {cnt=5, val=51, word=c} |       1691551246788 |       1691551246152 |2023-02-24T16:06:21.166|
|       [1] |      0 | data-10abb5bc-0170-43ae-b6a... |         orc |         0 |     0 |            1 |                595 |     [a] |     [a] | {cnt=0, val=0, word=0} | {cnt=1, val=11, word=a} | {cnt=1, val=11, word=a} |       1691551246722 |       1691551246273 |2023-02-24T16:06:21.166|
|       [4] |      0 | data-2c9b7095-65b7-4013-a7a... |         orc |         0 |     0 |            1 |                593 |     [a] |     [a] | {cnt=0, val=0, word=0} | {cnt=4, val=12, word=a} | {cnt=4, val=12, word=a} |       1691551246321 |       1691551246109 |2023-02-24T16:06:21.166|
+-----------+--------+--------------------------------+-------------+-----------+-------+--------------+--------------------+---------+---------+------------------------+-------------------------+-------------------------+---------------------+---------------------+-----------------------+
6 rows in set
*/

-- You can also query the files with specific snapshot
SELECT * FROM my_table$files /*+ OPTIONS('scan.snapshot-id'='1') */;

/*
+-----------+--------+--------------------------------+-------------+-----------+-------+--------------+--------------------+---------+---------+------------------------+-------------------------+-------------------------+---------------------+---------------------+-----------------------+
| partition | bucket |                      file_path | file_format | schema_id | level | record_count | file_size_in_bytes | min_key | max_key |      null_value_counts |         min_value_stats |         max_value_stats | min_sequence_number | max_sequence_number |         creation_time |
+-----------+--------+--------------------------------+-------------+-----------+-------+--------------+--------------------+---------+---------+------------------------+-------------------------+-------------------------+---------------------+---------------------+-----------------------+
|       [3] |      0 | data-8f64af95-29cc-4342-adc... |         orc |         0 |     0 |            1 |                593 |     [c] |     [c] | {cnt=0, val=0, word=0} | {cnt=3, val=33, word=c} | {cnt=3, val=33, word=c} |       1691551246234 |       1691551246637 |2023-02-24T16:06:21.166|
|       [2] |      0 | data-8b369068-0d37-4011-aa5... |         orc |         0 |     0 |            1 |                593 |     [b] |     [b] | {cnt=0, val=0, word=0} | {cnt=2, val=22, word=b} | {cnt=2, val=22, word=b} |       1691551246233 |       1691551246732 |2023-02-24T16:06:21.166|
|       [1] |      0 | data-10abb5bc-0170-43ae-b6a... |         orc |         0 |     0 |            1 |                595 |     [a] |     [a] | {cnt=0, val=0, word=0} | {cnt=1, val=11, word=a} | {cnt=1, val=11, word=a} |       1691551246267 |       1691551246798 |2023-02-24T16:06:21.166|
+-----------+--------+--------------------------------+-------------+-----------+-------+--------------+--------------------+---------+---------+------------------------+-------------------------+-------------------------+---------------------+---------------------+-----------------------+
3 rows in set
*/

Tags Table #

You can query the tag history information of the table through tags table, including which snapshots are the tags based on and some historical information of the snapshots. You can also get all tag names and time travel to a specific tag data by name.

SELECT * FROM my_table$tags;

/*
+----------+-------------+-----------+-------------------------+--------------+--------------+
| tag_name | snapshot_id | schema_id |             commit_time | record_count |   branches   |
+----------+-------------+-----------+-------------------------+--------------+--------------+
|     tag1 |           1 |         0 | 2023-06-28 14:55:29.344 |            3 |      []      |
|     tag3 |           3 |         0 | 2023-06-28 14:58:24.691 |            7 |  [branch-1]  |
+----------+-------------+-----------+-------------------------+--------------+--------------+
2 rows in set
*/

Consumers Table #

You can query all consumers which contains next snapshot.

SELECT * FROM my_table$consumers;

/*
+-------------+------------------+
| consumer_id | next_snapshot_id |
+-------------+------------------+
|         id1 |                1 |
|         id2 |                3 |
+-------------+------------------+
2 rows in set
*/

Manifests Table #

You can query all manifest files contained in the latest snapshot or the specified snapshot of the current table.

-- Query the manifest of latest snapshot
SELECT * FROM my_table$manifests;

/*
+--------------------------------+-------------+------------------+-------------------+---------------+
|                      file_name |   file_size |  num_added_files | num_deleted_files |     schema_id |
+--------------------------------+-------------+------------------+-------------------+---------------+
| manifest-f4dcab43-ef6b-4713... |        12365|               40 |                 0 |             0 |
| manifest-f4dcab43-ef6b-4713... |        1648 |                1 |                 0 |             0 |
+--------------------------------+-------------+------------------+-------------------+---------------+
2 rows in set
*/

-- You can also query the manifest with specified snapshot
SELECT * FROM my_table$manifests /*+ OPTIONS('scan.snapshot-id'='1') */;
/*
+--------------------------------+-------------+------------------+-------------------+---------------+
|                      file_name |   file_size |  num_added_files | num_deleted_files |     schema_id |
+--------------------------------+-------------+------------------+-------------------+---------------+
| manifest-f4dcab43-ef6b-4713... |        12365|               40 |                 0 |             0 |
+--------------------------------+-------------+------------------+-------------------+---------------+
1 rows in set
*/

Aggregation fields Table #

You can query the historical aggregation of the table through aggregation fields table.

SELECT * FROM my_table$aggregation_fields;

/*
+------------+-----------------+--------------+--------------------------------+---------+
| field_name |      field_type |    function  |               function_options | comment |
+------------+-----------------+--------------+--------------------------------+---------+
| product_id | BIGINT NOT NULL |           [] |                             [] |  <NULL> |
|      price |             INT | [true,count] | [fields.price.ignore-retrac... |  <NULL> |
|      sales |          BIGINT |        [sum] | [fields.sales.aggregate-fun... |  <NULL> |
+------------+-----------------+--------------+--------------------------------+---------+
3 rows in set
*/

Partitions Table #

You can query the partition files of the table.

SELECT * FROM my_table$partitions;

/*
+---------------+----------------+--------------------+--------------------+------------------------+
|  partition    |   record_count |  file_size_in_bytes|          file_count|        last_update_time|
+---------------+----------------+--------------------+--------------------+------------------------+
|  [1]          |           1    |             645    |                1   | 2024-06-24 10:25:57.400|
+---------------+----------------+--------------------+--------------------+------------------------+
*/

Global System Table #

Global system tables contain the statistical information of all the tables exists in paimon. For convenient of searching, we create a reference system database called sys. We can display all the global system tables by sql in flink:

USE sys;
SHOW TABLES;

ALL Options Table #

This table is similar to Options Table, but it shows all the table options is all database.

SELECT * FROM sys.all_table_options;

/*
+---------------+--------------------------------+--------------------------------+------------------+
| database_name |                     table_name |                            key |            value |
+---------------+--------------------------------+--------------------------------+------------------+
|         my_db |                    Orders_orc  |                         bucket |               -1 |
|         my_db |                        Orders2 |                         bucket |               -1 |
|         my_db |                        Orders2 |               sink.parallelism |                7 |
|         my_db2|                      OrdersSum |                         bucket |                1 |
+---------------+--------------------------------+--------------------------------+------------------+
7 rows in set
*/

Catalog Options Table #

You can query the catalog’s option information through catalog options table. The options not shown will be the default value. You can take reference to Configuration.

SELECT * FROM sys.catalog_options;

/*
+-----------+---------------------------+
|       key |                     value |
+-----------+---------------------------+
| warehouse | hdfs:///path/to/warehouse |
+-----------+---------------------------+
1 rows in set
*/