Parse FOR TIMESTAMP AS OF and FOR VERSION AS OF table versions - #2486
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rexminnis wants to merge 2 commits into
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Parse FOR TIMESTAMP AS OF and FOR VERSION AS OF table versions#2486rexminnis wants to merge 2 commits into
rexminnis wants to merge 2 commits into
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Trino (the SQL engine that descends from Presto) follows the standard closely, and most of what it needs is already an opt-in hook: double-quoted identifiers only, FILTER on aggregates, GROUP BY expressions and grouping sets, lambdas, MATCH_RECOGNIZE, table versioning, parenthesized EXPLAIN options, named table-function arguments with =>, and COMMENT ON. The test corpus covers the constructs a Trino user writes daily. Not covered yet: the FOR prefix on TIMESTAMP/VERSION AS OF (time travel), ROW types with named fields, and inline WITH FUNCTION routines.
Trino spells time travel on Iceberg and Delta tables with a leading FOR: FOR TIMESTAMP AS OF <expr> and FOR VERSION AS OF <snapshot id | branch>. The parser already accepts the Databricks forms without FOR behind supports_table_versioning; these two variants join them behind a new supports_for_table_version hook that TrinoDialect opts into, with their own Display, so a statement round-trips in the spelling its engine accepts. Databricks keeps rejecting the FOR forms.
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Stacked on #2485; only the last commit is new here, and I will rebase once that one lands.
Trino spells time travel on Iceberg and Delta tables with a leading
FOR:https://trino.io/docs/current/connector/iceberg.html#time-travel-queries
The parser already accepts the Databricks forms without
FORbehindsupports_table_versioning. This addsTableVersion::ForTimestampAsOfandTableVersion::ForVersionAsOfwith their ownDisplay, behind a newDialect::supports_for_table_versionhook thatTrinoDialectopts into, so a statement round-trips in the spelling its engine accepts.VERSION AS OFkeeps its numeric-only argument; theFORform takes an expression because Iceberg accepts a branch or tag name there. Databricks keeps rejecting theFORforms, as its existing test asserts.One pre-existing issue noticed on the way, left for a separate change: an alias after a version clause parses, but the canonical form prints the alias first (
t AS a FOR VERSION AS OF 1), which no engine accepts.