feat: batch per-column PII tag ALTERs into multi-action statements#33
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Collapse per-column ALTER TABLE ... MODIFY COLUMN ... SET/UNSET TAG into single multi-action ALTER TABLE statements (SET and UNSET kept separate), no-op on empty, chunked at 100 actions/statement to stay under Snowflake's statement-size limit. Cuts cloud-services cost from dozens of statements per table to a handful. Old _set_column_tag/_unset_column_tag retained as single-element shims for backward compatibility.
…umns; UNSET one stmt per column)
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Resolved the batched-ALTER grammar open item — all forms now live-validated against Snowflake (8/8 checks pass). Final grammar (asymmetric, per Snowflake):
The earlier multi-column-UNSET emission (which Snowflake rejected) is fixed: |
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What
Collapses per-column
ALTER TABLE ... MODIFY COLUMN ... SET/UNSET TAGinto single multi-actionALTER TABLEstatements during PII tag sync.SETandUNSETare kept as separate statements, no-op on empty, and chunked at 100 actions/statement to stay under Snowflake's statement-size limit.Why
Wide tables previously emitted dozens of individual
ALTERstatements per sync — one per column tag change. Batching cuts that to a handful, reducing cloud-services cost by roughly 20-40x on wide tables.Compatibility
The old
_set_column_tag/_unset_column_tagare retained as single-element shims, so existing callers keep working unchanged.Tests
60 tests pass (
uv run pytest),ruff checkclean.The multi-column
ALTER TABLE ... MODIFY COLUMN ...batched syntax was validated only against mocked cursors — the agent's Snowflake MCP access is read-only, so no live execution was possible. A reviewer or the author must smoke-test the generated multi-action ALTER against a scratch table in a writable dev schema before merging to confirm Snowflake accepts the batched statement shape.