From 9012ae141def2e4698d43692acf07a8178d55233 Mon Sep 17 00:00:00 2001 From: Corey Huinker Date: Thu, 12 Nov 2026 13:23:26 -0500 Subject: [PATCH v19842.2 2/3] pg_dump: Map mismatched-NULL values arrays to empty array. As reported in two bugs, in versions prior to v19 it is possible for range_length_histogram to be NULL when range_empty_frac is NOT NULL and for most_common_elems to be NULL when most_common_freqs is NOT NULL. This is solved in v19 where the NULL values are now empty arrays, so pg_dump must make the same mapping when exporting stats from earlier versions. Bug: #19842 Reported-by: chunling qin <303677365@qq.com> Discussion: https://postgr.es/m/19842-6e808a09ff4b75d2@postgresql.org Bug: #19857 Reported-by: Atish Prakash <125atishprak@gmail.com> Discussion: https://postgr.es/m/19857-6e808a09ff4b75d2@postgresql.org Author: Corey Huinker Backpatch-through: 19 --- src/bin/pg_dump/pg_dump.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c index a3f38f3b886..dbb49506f83 100644 --- a/src/bin/pg_dump/pg_dump.c +++ b/src/bin/pg_dump/pg_dump.c @@ -11341,6 +11341,13 @@ dumpRelationStats_dumper(Archive *fout, const void *userArg, const TocEntry *te) pg_fatal("could not find index attname \"%s\"", attname); } + /* + * Prior to v19, range_length_histogram and most_common_elems could + * have a NULL value while corresponding stanumbers field + * (range_empty_frac and most_common_elem_freqs, respectively) had a + * NOT NULL value. Those values are represented as an empty array + * going forward. + */ if (!PQgetisnull(res, rownum, i_inherited)) appendNamedArgument(out, fout, "inherited", "boolean", PQgetvalue(res, rownum, i_inherited)); @@ -11368,6 +11375,8 @@ dumpRelationStats_dumper(Archive *fout, const void *userArg, const TocEntry *te) if (!PQgetisnull(res, rownum, i_most_common_elems)) appendNamedArgument(out, fout, "most_common_elems", "text", PQgetvalue(res, rownum, i_most_common_elems)); + else if (fout->remoteVersion < 190000 && !PQgetisnull(res, rownum, i_most_common_elem_freqs)) + appendNamedArgument(out, fout, "most_common_elems", "text", "{}"); if (!PQgetisnull(res, rownum, i_most_common_elem_freqs)) appendNamedArgument(out, fout, "most_common_elem_freqs", "real[]", PQgetvalue(res, rownum, i_most_common_elem_freqs)); @@ -11379,6 +11388,8 @@ dumpRelationStats_dumper(Archive *fout, const void *userArg, const TocEntry *te) if (!PQgetisnull(res, rownum, i_range_length_histogram)) appendNamedArgument(out, fout, "range_length_histogram", "text", PQgetvalue(res, rownum, i_range_length_histogram)); + else if (fout->remoteVersion < 190000 && !PQgetisnull(res, rownum, i_range_empty_frac)) + appendNamedArgument(out, fout, "range_length_histogram", "text", "{}"); if (!PQgetisnull(res, rownum, i_range_empty_frac)) appendNamedArgument(out, fout, "range_empty_frac", "real", PQgetvalue(res, rownum, i_range_empty_frac)); @@ -18718,7 +18729,27 @@ dumpStatisticsExtStats(Archive *fout, const StatsExtInfo *statsextinfo) " 'most_common_freqs', ee.most_common_freqs::text, " " 'histogram_bounds', ee.histogram_bounds::text, " " 'correlation', ee.correlation::text, " - " 'most_common_elems', ee.most_common_elems::text, " + " 'most_common_elems', "); + + /* + * In versions prior to v19, most_common_elems could be NULL when + * most_common_elem_freqs was NOT NULL. In such cases the NULL + * value should be replaced with the empty array "{}". + * + * The field range_length_histogram was not yet present in + * pg_stats_ext_exprs until v19, otherwise it would have had the + * same issue. + */ + if (fout->remoteVersion >= 190000) + appendPQExpBufferStr(pq, "ee.most_common_elems::text, "); + else + appendPQExpBufferStr(pq, "CASE " + " WHEN ee.most_common_elem_freqs IS NOT NULL " + " THEN coalesce(ee.most_common_elems::text, '{}'::text) " + " ELSE ee.most_common_elems::text " + "END, "); + + appendPQExpBufferStr(pq, " 'most_common_elem_freqs', ee.most_common_elem_freqs::text, " " 'elem_count_histogram', ee.elem_count_histogram::text"); -- 2.56.0