Schema Diff: drop the scaffolding default partition after rebuilding a partitioned table - #10316
Schema Diff: drop the scaffolding default partition after rebuilding a partitioned table#10316dpage wants to merge 3 commits into
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Included review availability: Your plan provides up to 8 included reviews per hour; 6 remain after this review. WalkthroughSchema Diff now rebuilds partitioned tables without mutating comparison data. PostgreSQL and PPAS templates conditionally create and remove temporary default partitions while preserving unmatched rows. Regression coverage validates rebuild results. Module registration now removes duplicate references. ChangesPartition default scaffolding
Module registration deduplication
Estimated code review effort: 3 (Moderate) | ~30 minutes Merge Risk: 🔵 Low · up to The rebuild now removes only temporary default partitions and preserves genuine defaults and unmatched rows. It is mergeable with owner awareness because an interruption or concurrent write during the multi-step replacement could still leave the rebuilt table in a partial state. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
Full details: Linked Issues checkExplanation The changes satisfy issue Full details: Out of Scope Changes checkExplanation All changes support the Schema Diff partition rebuild fix. The data-copy protection, partition diff handling, submodule deduplication, and regression tests address repeated generation and metadata mutation related to the same rebuild workflow. ✨ Finishing Touches🧪 Generate unit tests (beta)
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Inline comments:
In
`@web/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/pg/default/partition_diff.sql`:
- Around line 4-16: Update the scaffold default-partition name in both
web/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/pg/default/partition_diff.sql
lines 4-16 and
web/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/ppas/default/partition_diff.sql
lines 4-16 to derive it from the randomized temporary table name, and use that
same unique name for creation and DROP TABLE cleanup; no other changes are
needed.
- Around line 12-16: Before dropping the scaffolding default partition, validate
that it is empty and abort if it contains rows; update the conditional block in
partition_diff.sql for both
web/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/pg/default/partition_diff.sql
lines 12-16 and
web/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/ppas/default/partition_diff.sql
lines 12-16. Preserve the existing DROP TABLE behavior only for an empty
scaffold.
In `@web/pgadmin/tools/schema_diff/tests/test_schema_diff_partition_default.py`:
- Around line 37-81: Extend the schema-diff fixture test around DDL_SOURCE and
DDL_TARGET to insert rows into both the regular and DEFAULT partitions of each
target table before rebuilding. After each rebuild, assert the expected row
counts in the corresponding partitions, covering INSERT ... SELECT data copying
and routing for both partition configurations.
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web/pgadmin/browser/server_groups/servers/databases/schemas/tables/partitions/__init__.pyweb/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/pg/default/partition_diff.sqlweb/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/partitions/sql/ppas/default/partition_diff.sqlweb/pgadmin/tools/schema_diff/tests/test_schema_diff_partition_default.py
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scaffold default partitions, and skip redundant partition ALTER diff Address CodeRabbit review findings on the partitioned-table rebuild added in pgadmin-org#10301: - The scaffolding default partition's name was derived from the original table's name (<table>_default), a deterministic name that can collide with an existing relation. Derive it from the already string.randomised temporary table name instead, matching the collision-avoidance convention already used for the temp partitioned table and its temp partitions. - The scaffolding default partition was unconditionally dropped once the row copy finished. Any row from the source table that fell outside every real partition's bounds landed in that scaffold and was silently destroyed. The generated SQL now only drops the scaffold if it is still empty; otherwise it is kept, so the rows it caught survive as the default partition of the rebuilt table. - Separately, found and fixed a data-loss bug this exposed: whenever a table's partitions differ on both source and target, the generic table-diff also ran its own ALTER-based partition add/remove/detach logic (get_sql_from_table_diff/_check_for_partitions_in_sql) alongside the full-table rebuild path in schema_diff_table_utils.py. Because that generic path detaches a bound-changed partition using its real name before the rebuild's row-copy INSERT ... SELECT runs against the original table, the detached partition's rows were invisible to that copy and got dropped when the rebuild's own cleanup step removed the now-standalone table - causing the run-python-tests-pg/run-feature-tests-pg CI failures on PR pgadmin-org#10316. The generic partition diffing is now skipped whenever both sides are partitioned, since the rebuild path already handles every partition difference itself. - Strengthened the regression test: both fixtures now carry real rows (including rows that only fit a DEFAULT partition, and a row outside every rebuilt partition's bounds) so the row-copy and row-routing paths are actually exercised, not just the DDL shape.
…a partitioned table (pgadmin-org#10301) Rebuilding a partitioned table (e.g. because its partition key changed) generates a script that creates a temporary partitioned table, adds a DEFAULT partition to it purely so the row-copy INSERT doesn't fail on rows that match none of the real partitions, copies the rows across and renames everything into place. The scaffolding DEFAULT partition was never removed, so a source table with no default partition of its own ended up with an extra one in the rebuilt target, and Schema Diff would report the table as different forever after. Worse, if the source table did have a genuine default partition, the generated script tried to create it as well as the scaffolding one, and Postgres only allows a single DEFAULT partition per parent, so applying the script failed outright. get_sql_from_diff() now checks whether the source table already has a default partition and only asks the template to scaffold one when it doesn't; partition_diff.sql only creates that scaffolding partition (and drops it again once the row copy is done) in that case, leaving a genuine source default partition to be carried across, renamed into place, by the normal per-partition rename loop. Added test_schema_diff_partition_default.py, covering both a source table without a default partition (the scaffolding one must be dropped) and one with a genuine default partition (it must survive and the script must not attempt to create two).
scaffold default partitions, and skip redundant partition ALTER diff Address CodeRabbit review findings on the partitioned-table rebuild added in pgadmin-org#10301: - The scaffolding default partition's name was derived from the original table's name (<table>_default), a deterministic name that can collide with an existing relation. Derive it from the already string.randomised temporary table name instead, matching the collision-avoidance convention already used for the temp partitioned table and its temp partitions. - The scaffolding default partition was unconditionally dropped once the row copy finished. Any row from the source table that fell outside every real partition's bounds landed in that scaffold and was silently destroyed. The generated SQL now only drops the scaffold if it is still empty; otherwise it is kept, so the rows it caught survive as the default partition of the rebuilt table. - Separately, found and fixed a data-loss bug this exposed: whenever a table's partitions differ on both source and target, the generic table-diff also ran its own ALTER-based partition add/remove/detach logic (get_sql_from_table_diff/_check_for_partitions_in_sql) alongside the full-table rebuild path in schema_diff_table_utils.py. Because that generic path detaches a bound-changed partition using its real name before the rebuild's row-copy INSERT ... SELECT runs against the original table, the detached partition's rows were invisible to that copy and got dropped when the rebuild's own cleanup step removed the now-standalone table - causing the run-python-tests-pg/run-feature-tests-pg CI failures on PR pgadmin-org#10316. The generic partition diffing is now skipped whenever both sides are partitioned, since the rebuild path already handles every partition difference itself. - Strengthened the regression test: both fixtures now carry real rows (including rows that only fit a DEFAULT partition, and a row outside every rebuilt partition's bounds) so the row-copy and row-routing paths are actually exercised, not just the DDL shape.
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Rebased onto current |
The generated Schema Diff script for a partitioned table rebuild could
come out referring to a relation that has never existed, along the lines
of:
CREATE TABLE schema.temp_partitioned_2 (
LIKE schema.temp_partitioned_1 INCLUDING ALL
) PARTITION BY RANGE (col1);
so that applying it fails with 'relation "schema.temp_partitioned_1"
does not exist'.
There are two things going on here, and both are fixed.
PgAdminModule.register() is called once per application instance, whilst
the blueprint objects themselves are module level singletons, so each
sub-class that appends its sub-modules from its own register() (most of
them do, TableModule included) leaves a duplicate entry behind every
time a second application is created in the same process. Nothing in
production notices, because production creates a single app, but the
regression suite creates several, and anything walking self.submodules
then does its work once per duplicate: with four copies of the partition
sub-module, get_sql_from_submodule_diff generated the same partition
rebuild four times over. self.submodules is now de-duplicated as the
blueprint registers, and parentmodules likewise only gains an entry it
does not already hold.
The second call was only harmful because PartitionsView.get_sql_from_diff
stashed its temporary names on the caller's own dictionaries, replacing
the table's real name with a temporary one, so a subsequent call read the
first call's temporary name back as the original. It now works on copies
and leaves the comparison data it is handed alone, which makes it safe to
call more than once regardless of how it is reached.
|
Pushed a fix for the failing
The repeat was only fatal because Both levels are fixed: Note that the same fix is on #10305, which was failing for the same reason; whichever of the two lands second will carry an identical change. |
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What this is
Rebuilding a partitioned table (e.g. because its partition key changed) generates a script that creates a temporary partitioned table, adds a
DEFAULTpartition to it purely so the row-copyINSERTdoesn't fail on rows that match none of the real partitions, copies the rows across, and renames everything into place. The scaffoldingDEFAULTpartition was never removed, so a source table with no default partition of its own ended up with an extra one in the rebuilt target, and Schema Diff reported the table as different forever after.Worse, if the source table did have a genuine default partition, the generated script tried to create it as well as the scaffolding one, and PostgreSQL only allows a single
DEFAULTpartition per parent, so applying the script failed outright.The fix
get_sql_from_diff()now checks whether the source table already has a default partition and only asks the template to scaffold one when it doesn't;partition_diff.sqlonly creates that scaffolding partition (and drops it again once the row copy is done) in that case, leaving a genuine source default partition to be carried across, renamed into place, by the normal per-partition rename loop.Testing
Added
test_schema_diff_partition_default.py, covering both a source table without a default partition (the scaffolding one must be dropped) and one with a genuine default partition (it must survive and the script must not attempt to create two).tools.schema_diffandbrowser.server_groups.servers.databases.schemas.tables(473 tests) pass against PostgreSQL 18;pycodestyleis clean.Fixes #10301.
Summary by CodeRabbit
Bug Fixes
Tests