schemachanger: allow dropping column referenced in partial index predicate#169753
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schemachanger: allow dropping column referenced in partial index predicate#169753rafiss wants to merge 1 commit intocockroachdb:masterfrom
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…icate The declarative schema changer previously rejected ALTER TABLE ... DROP COLUMN if the column was referenced in a partial index predicate, with a hint to drop the index first. The restriction was added in cockroachdb#97372 as a temporary safeguard for cockroachdb#96924, where the optimizer could need to read a column being dropped to evaluate the predicate when both the column and its dependent partial index were transitioning simultaneously. The dep rule "secondary index partial no longer public before referenced column" (added later) sequences the partial index into DELETE_ONLY before the column reaches WRITE_ONLY. In DELETE_ONLY the index issues blind DELs and does not need to evaluate its predicate, so the original hazard no longer applies for the declarative path. This commit lifts the restriction in the declarative DROP COLUMN path only. The legacy schema changer keeps the restriction (it lacks the dep-rule machinery), and partial unique-without-index predicates remain blocked in both schema changers — those will be addressed separately. ALTER PRIMARY KEY and ALTER COLUMN TYPE also keep the restriction, because their column-drop traversal can encounter element types that the existing walker does not yet handle. The restriction toggle on walkColumnDependencies changes from a bool to a small predicateRefPolicy enum (allow all / disallow UWI only / disallow all) so each caller can pick the policy that matches its actual constraints. The DML-injection test case "drop column with partial index" was re-enabled (previously skipped under cockroachdb#97813). Resolves: cockroachdb#97813 Epic: none Release note (sql change): ALTER TABLE ... DROP COLUMN no longer rejects columns referenced in a partial index predicate. The dependent partial index is dropped automatically as part of the same statement. The previous behavior — requiring the user to drop the index first — is still in effect when the legacy schema changer is in use, and when the column is referenced in a partial UNIQUE WITHOUT INDEX predicate. Co-Authored-By: roachdev-claude <roachdev-claude-bot@cockroachlabs.com>
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The declarative schema changer previously rejected ALTER TABLE ... DROP COLUMN if the column was referenced in a partial index predicate, with a hint to drop the index first. The restriction was added in #97372 as a temporary safeguard for #96924, where the optimizer could need to read a column being dropped to evaluate the predicate when both the column and its dependent partial index were transitioning simultaneously.
The dep rule "secondary index partial no longer public before referenced column" (added later) sequences the partial index into DELETE_ONLY before the column reaches WRITE_ONLY. In DELETE_ONLY the index issues blind DELs and does not need to evaluate its predicate, so the original hazard no longer applies for the declarative path.
This commit lifts the restriction in the declarative DROP COLUMN path only. The legacy schema changer keeps the restriction (it lacks the dep-rule machinery), and partial unique-without-index predicates remain blocked in both schema changers — those will be addressed separately. ALTER PRIMARY KEY and ALTER COLUMN TYPE also keep the restriction, because their column-drop traversal can encounter element types that the existing walker does not yet handle.
The restriction toggle on walkColumnDependencies changes from a bool to a small predicateRefPolicy enum (allow all / disallow UWI only / disallow all) so each caller can pick the policy that matches its actual constraints.
The DML-injection test case "drop column with partial index" was re-enabled (previously skipped under #97813).
Resolves: #97813
Epic: none
Release note (sql change): ALTER TABLE ... DROP COLUMN no longer rejects columns referenced in a partial index predicate. The dependent partial index is dropped automatically as part of the same statement. The previous behavior — requiring the user to drop the index first — is still in effect when the legacy schema changer is in use, and when the column is referenced in a partial UNIQUE WITHOUT INDEX predicate.