Implement same-table concurrency using Postgres CTID column. #410
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marcocitus
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Jul 31, 2023
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High level note: Not all table access methods naturally support TID Scan (e.g. Citus Columnar does not), in which case this approach is probably much worse than a single-threaded full table scan.
Might be best to limit to heap / an allowlist of table access methods.
dimitri
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The Postgres system column "ctid" is the physical location of the row version within its table. It is encoded using the tid datatype: `(pagenumber,rownumber)`. Every single Postgres table has a "ctid" column and it is always possible to split a table's contents by using ctid based ranges. The question of this approach being good at reducing pgcopydb timings remains open: this PR is meant for allowing more experimentations.
TID scan might not be supported by other Table AM (such as Citus Columnar).
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The Postgres system column "ctid" is the physical location of the row version within its table. It is encoded using the tid datatype:
(pagenumber,rownumber).Every single Postgres table has a "ctid" column and it is always possible to split a table's contents by using ctid based ranges. The question of this approach being good at reducing pgcopydb timings remains open: this PR is meant for allowing more experimentations.