PG doc: add note on statistics and snapshotting in PG considerations#35804
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martykulma wants to merge 2 commits intoMaterializeInc:mainfrom
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PG doc: add note on statistics and snapshotting in PG considerations#35804martykulma wants to merge 2 commits intoMaterializeInc:mainfrom
martykulma wants to merge 2 commits intoMaterializeInc:mainfrom
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left a suggestion (feel free to ignore if I missed the point) and a question.
| using ranges of | ||
| [`CTID`](https://www.postgresql.org/docs/current/ddl-system-columns.html#DDL-SYSTEM-COLUMNS-CTID). | ||
| Materialize uses [estimates](https://www.postgresql.org/docs/current/row-estimation-examples.html) | ||
| for the amount of data and rows that will be read. Missing or stale statistics will result in |
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Not sure but maybe?
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.
Also, do you think in the actual postgres ingest tutorials, we should mention this Analyze step?
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Are the tutorials you're referencing the vendor specific steps (e.g. https://preview.materialize.com/materialize/35804/ingest-data/postgres/alloydb/)? I put it in considerations as that section appears for each of the vendors. If there's another tutorials area, seems like we may want to put it there as well!
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Adds a section in PostgreSQL source considerations to highlight the relationship between parallel snapshot, console snapshot reporting, and up to date PostgreSQL table statistics.