Pin PostgreSQL 19 parallel autovacuum on a columnar table (#398)

docs/limitations.md

@@ -268,10 +268,22 @@ returning no rows.
 
 ## Vacuum and compaction
 
+<<<<<<< HEAD
+- `autovacuum_parallel_workers`, the per-table storage parameter PostgreSQL 19 adds
+  for parallel autovacuum, is accepted on a columnar table and has no effect.
+  pgColumnar implements its own vacuum, which marks the visibility map and retires
+  fully-deleted row groups, and does no parallel work. The parameter cannot be
+  refused: storage-parameter validation belongs to PostgreSQL and is driven by the
+  relation kind rather than by the access method. Setting it is harmless and
+  pointless.
+- `VACUUM FULL` and `CLUSTER` are not supported on a columnar table; the
+  copy-for-cluster path raises an error. Use `pgcolumnar.vacuum` or
+=======
 - `REPACK`, `VACUUM FULL` and `CLUSTER` are not supported on a columnar table; the
   copy-for-cluster path raises an error. `REPACK` arrives in PostgreSQL 19 and
   replaces the other two, and it dispatches through the same path, so it is
   refused for the same reason. Use `pgcolumnar.vacuum` or
+>>>>>>> origin/main
   `pgcolumnar.vacuum_full` instead.
 - `pgcolumnar.vacuum` always rewrites the whole relation into full row groups. It
   accepts a `stripe_count` argument for compatibility with the interface, but it

test/pg19_vacuum_options.sh

@@ -0,0 +1,93 @@
+#!/usr/bin/env bash
+#
+# PostgreSQL 19 parallel autovacuum, on a columnar table (issue #398).
+#
+# 19 adds parallel autovacuum: a server variable autovacuum_max_parallel_workers
+# and a per-table storage parameter autovacuum_parallel_workers. pgColumnar
+# implements its own relation_vacuum callback, so the question was whether a table
+# access method participates in that at all.
+#
+# Measured answer: the storage parameter is ACCEPTED on a columnar table and lands
+# in pg_class.reloptions exactly as it does on heap, and it has NO EFFECT, because
+# pgcolumnar_relation_vacuum marks the visibility map and retires fully-deleted
+# row groups and does no parallel work of any kind. A parameter a user can set and
+# that silently does nothing is worth pinning, so it is recorded here and in
+# docs/limitations.md rather than left to be discovered.
+#
+# It cannot simply be rejected. Storage-parameter validation is core's, driven by
+# relkind rather than by the access method, and pgColumnar has no reloptions hook
+# to refuse it from. Documenting it is the available honest option.
+#
+# The heap arm is a control rather than decoration: without it, "the parameter does
+# nothing here" cannot be told apart from "parallel autovacuum does nothing on this
+# cluster", and autovacuum_max_parallel_workers defaults to 0 on 19beta2, which
+# would make the second reading true for everyone.
+#
+# Usage:  test/pg19_vacuum_options.sh [PG_CONFIG]
+# Written fresh for pgColumnar.
+
+set -uo pipefail
+. "$(dirname "${BASH_SOURCE[0]}")/lib.sh"
+
+pgc_setup "${1:-/usr/local/pg19/bin/pg_config}"
+
+srv="$(q 'SHOW server_version_num')"
+if [ "${srv:-0}" -lt 190000 ]; then
+	echo "SKIP  parallel autovacuum requires PostgreSQL 19 (server_version_num=$srv)"
+	echo "pg19_vacuum_options.sh: SKIPPED"
+	exit 0
+fi
+
+ROWS=${PGC_AV_ROWS:-100000}
+
+psql_run "CREATE TABLE av_c (id int, v text) USING pgcolumnar;
+	CREATE TABLE av_h (id int, v text);
+	INSERT INTO av_c SELECT g,'x'||g FROM generate_series(1,$ROWS) g;
+	INSERT INTO av_h SELECT g,'x'||g FROM generate_series(1,$ROWS) g;
+	DELETE FROM av_c WHERE id % 4 = 0;
+	DELETE FROM av_h WHERE id % 4 = 0;"
+
+# ---- the setting exists, and is off by default -------------------------------
+check "autovacuum_max_parallel_workers exists on this server" \
+	"$(q 'SHOW autovacuum_max_parallel_workers' >/dev/null 2>&1 && echo yes || echo no)" "yes"
+
+# ---- the storage parameter is accepted on BOTH access methods ----------------
+# This is the answer to the issue: a table AM does not get to refuse it.
+for t in av_c av_h; do
+	out="$(psql_run "ALTER TABLE $t SET (autovacuum_parallel_workers = 3);" 2>&1)"
+	check "autovacuum_parallel_workers is accepted on $t" \
+		"$(case "$out" in *ERROR*) grep -oE 'ERROR:.*' <<<"$out" | head -1 ;; *) echo accepted ;; esac)" \
+		"accepted"
+	check "and it is recorded in reloptions for $t" \
+		"$(q "SELECT array_to_string(reloptions,',') FROM pg_class WHERE relname='$t'")" \
+		"autovacuum_parallel_workers=3"
+done
+
+# ---- and it changes nothing about what our vacuum does -----------------------
+# Same live rows before and after, with the parameter set. The point is not that
+# vacuum works; it is that setting the parameter neither helps nor breaks it.
+live_before="$(q 'SELECT count(*) FROM av_c')"
+hash_before="$(q "SELECT md5(string_agg(id::text||':'||v, ',' ORDER BY id)) FROM av_c")"
+
+check "VACUUM on a columnar table with the parameter set succeeds" \
+	"$(psql_run 'VACUUM av_c;' 2>&1 | grep -c 'ERROR' || true)" "0"
+check "VACUUM (PARALLEL 2) on a columnar table succeeds" \
+	"$(psql_run 'VACUUM (PARALLEL 2) av_c;' 2>&1 | grep -c 'ERROR' || true)" "0"
+check "pgcolumnar.vacuum with the parameter set succeeds" \
+	"$(psql_run "SELECT pgcolumnar.vacuum('av_c');" 2>&1 | grep -c 'ERROR' || true)" "0"
+
+check "the rows are unchanged by any of it" "$(q 'SELECT count(*) FROM av_c')" "$live_before"
+check "and the content is unchanged" \
+	"$(q "SELECT md5(string_agg(id::text||':'||v, ',' ORDER BY id)) FROM av_c")" "$hash_before"
+
+# ---- the control: heap reports parallel vacuum activity, columnar does not ----
+# If a future release makes table AMs participate, this check flips and should be
+# rewritten to assert that our vacuum reports workers too.
+vh="$(psql_run 'VACUUM (VERBOSE) av_h;' 2>&1)"
+vc="$(psql_run 'VACUUM (VERBOSE) av_c;' 2>&1)"
+check "control: VACUUM VERBOSE reports on the heap table" \
+	"$(grep -qi 'finished vacuuming' <<<"$vh" && echo yes || echo no)" "yes"
+check "columnar VACUUM VERBOSE reports nothing, because the AM path is ours" \
+	"$(grep -qi 'finished vacuuming .*av_c' <<<"$vc" && echo "reports" || echo "silent")" "silent"
+
+pgc_summary

test/run_all_versions.sh

@@ -208,7 +208,7 @@ SRCDIR="${PGC_RUN_SRCDIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)}"
 SUITES=(harness_selftest docs_style smoke phase2 phase3 phase4 phase5 phase6 audit concurrency unique_conc \
 	differential recovery replication native_backend_crash fuzz fuzz_parquet fuzz_arrow hardening concurrent_diff parallel sorted_projection \
 	arrow_export parquet_export read_stream corruption \
-	generated_columns temporal arrow_import index_only projections arrow_nested parquet_import parquet_nested arrow_nested_import parquet_nested_import native_writer native_roundtrip native_encoding native_fastdecode native_zonemap write_minmax_fastpath write_fsst_compressed fsst_margin encode_invariants encode_effort native_skip pushdown_report native_agg native_agg_deletes native_agg_addcolumn native_groupagg ungrouped_vector_agg parallel_vector_agg native_bloom bloom_setting bloom_lazy native_vecskip native_index native_fetch_position native_dml alter_column_type native_ios native_projection native_cluster native_repack native_compact native_recluster recluster_extent native_vacuum_race native_sort_by sort_status native_reclaim native_ownership drop_cleanup pg_dump_roundtrip native_reclaim_cycles native_reclaim_frag native_reclaim_reconcile native_gap native_format native_truncate native_rewrite native_rewrite_conc rewrite_group_scan native_parquet_schema native_read_parquet native_parquet_fdw native_parquet_pushdown native_parquet_hardening server_file_privilege native_parquet_stack native_parquet_units native_parquet_flba native_parquet_codecs native_parquet_projection native_parquet_multifile native_parquet_streaming native_parquet_partition native_cancel cancel_decode wal_envelope decode_interrupts import_exclusion import_deferred parallel_copy parallel_export_parquet fk_referencing row_triggers native_lazy_slot native_ctas native_fetch_cache native_fetch_interrupt analyze_stats analyze_reltuples native_fetch_projection column_projection isolation)
+	generated_columns temporal arrow_import index_only projections arrow_nested parquet_import parquet_nested arrow_nested_import parquet_nested_import native_writer native_roundtrip native_encoding native_fastdecode native_zonemap write_minmax_fastpath write_fsst_compressed fsst_margin encode_invariants encode_effort native_skip pushdown_report native_agg native_agg_deletes native_agg_addcolumn native_groupagg ungrouped_vector_agg parallel_vector_agg native_bloom bloom_setting bloom_lazy native_vecskip native_index native_fetch_position native_dml alter_column_type native_ios native_projection native_cluster pg19_vacuum_options native_repack native_compact native_recluster recluster_extent native_vacuum_race native_sort_by sort_status native_reclaim native_ownership drop_cleanup pg_dump_roundtrip native_reclaim_cycles native_reclaim_frag native_reclaim_reconcile native_gap native_format native_truncate native_rewrite native_rewrite_conc rewrite_group_scan native_parquet_schema native_read_parquet native_parquet_fdw native_parquet_pushdown native_parquet_hardening server_file_privilege native_parquet_stack native_parquet_units native_parquet_flba native_parquet_codecs native_parquet_projection native_parquet_multifile native_parquet_streaming native_parquet_partition native_cancel cancel_decode wal_envelope decode_interrupts import_exclusion import_deferred parallel_copy parallel_export_parquet fk_referencing row_triggers native_lazy_slot native_ctas native_fetch_cache native_fetch_interrupt analyze_stats analyze_reltuples native_fetch_projection column_projection isolation)
 
 # Default matrix: one assert-enabled pg_config per major, 15 through 19.
 DEFAULT_CONFIGS=(