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PG doc: add note on statistics and snapshotting in PG considerations #35804

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PG doc: add note on statistics and snapshotting in PG considerations #35804

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PG doc: add note on statistics and snapshotting in PG considerations
martykulma Mar 31, 2026
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Reword from Kay
martykulma Mar 31, 2026
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19 changes: 19 additions & 0 deletions doc/user/data/postgres_source_details.yml
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Expand Up @@ -212,6 +212,20 @@
DELETE FROM t;
```

- name: postgres-snapshot-behavior
content: |
The PostgreSQL source performs parallel snapshotting of tables by distributing rows among
workers using ranges of
[`CTID`](https://www.postgresql.org/docs/current/ddl-system-columns.html#DDL-SYSTEM-COLUMNS-CTID).
Materialize uses
[PostgreSQL statistics to estimate](https://www.postgresql.org/docs/current/row-estimation-examples.html)
the amount of data and number of rows to read. Missing or stale statistics can result in uneven
work distribution, reducing snapshot performance. They can also cause incorrect snapshot
progress reporting in the Console.

To avoid this situation, before creating the source in Materialize, ensure statistics are up to
date by running PostgreSQL `ANALYZE` command.

- name: postgres-considerations
content: |
### Schema changes
Expand Down Expand Up @@ -279,3 +293,8 @@
### Modifying an existing source

{{% include-headless "/headless/alter-source-snapshot-blocking-behavior" %}}

### Snapshotting

{{% include-from-yaml data="postgres_source_details"
name="postgres-snapshot-behavior" %}}
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