From 98548efb5af50edc3f03444f8155f427e39fecd7 Mon Sep 17 00:00:00 2001 From: Corey Huinker Date: Tue, 4 Nov 2025 15:59:31 -0500 Subject: [PATCH v8 3/7] Refactor output format of pg_dependencies. The existing format of pg_dependencies uses a single-object JSON structure where each key is itself a comma-separated list of attnums. While this is a very compact format, it's confusing to read and is difficult to manipulate values within the object. This wasn't a concern until statistics import functions were introduced, enabling users to inject hypothetical statistics into an object to observe their effect on the query planner. The new format is an array of objects, each object must have the keys "attributes", which must contain an array of attnums, "dependency", which must be an integer, and "degree", which must be a float. The change in format is adequately described from the changes to src/test/regress/expected/stats_ext.out so description here is redundant. --- src/backend/statistics/dependencies.c | 29 ++++---- src/test/regress/expected/stats_ext.out | 95 ++++++++++++++++++++++--- src/test/regress/sql/stats_ext.sql | 7 +- 3 files changed, 104 insertions(+), 27 deletions(-) diff --git a/src/backend/statistics/dependencies.c b/src/backend/statistics/dependencies.c index eb2fc4366b4a..c150ddfb5944 100644 --- a/src/backend/statistics/dependencies.c +++ b/src/backend/statistics/dependencies.c @@ -671,34 +671,33 @@ pg_dependencies_out(PG_FUNCTION_ARGS) { bytea *data = PG_GETARG_BYTEA_PP(0); MVDependencies *dependencies = statext_dependencies_deserialize(data); - int i, - j; StringInfoData str; initStringInfo(&str); - appendStringInfoChar(&str, '{'); + appendStringInfoChar(&str, '['); - for (i = 0; i < dependencies->ndeps; i++) + for (int i = 0; i < dependencies->ndeps; i++) { MVDependency *dependency = dependencies->deps[i]; if (i > 0) appendStringInfoString(&str, ", "); - appendStringInfoChar(&str, '"'); - for (j = 0; j < dependency->nattributes; j++) - { - if (j == dependency->nattributes - 1) - appendStringInfoString(&str, " => "); - else if (j > 0) - appendStringInfoString(&str, ", "); + if (dependency->nattributes <= 1) + elog(ERROR, "invalid zero-length nattributes array in MVDependencies"); - appendStringInfo(&str, "%d", dependency->attributes[j]); - } - appendStringInfo(&str, "\": %f", dependency->degree); + appendStringInfo(&str, "{\"attributes\": [%d", + dependency->attributes[0]); + + for (int j = 1; j < dependency->nattributes - 1; j++) + appendStringInfo(&str, ", %d", dependency->attributes[j]); + + appendStringInfo(&str, "], \"dependency\": %d, \"degree\": %f}", + dependency->attributes[dependency->nattributes - 1], + dependency->degree); } - appendStringInfoChar(&str, '}'); + appendStringInfoChar(&str, ']'); PG_RETURN_CSTRING(str.data); } diff --git a/src/test/regress/expected/stats_ext.out b/src/test/regress/expected/stats_ext.out index 1d837badb96c..8cea29de3140 100644 --- a/src/test/regress/expected/stats_ext.out +++ b/src/test/regress/expected/stats_ext.out @@ -196,7 +196,8 @@ Statistics objects: "public.ab1_a_b_stats" ON a, b FROM ab1; STATISTICS 0 ANALYZE ab1; -SELECT stxname, jsonb_pretty(d.stxdndistinct::text::jsonb) AS stxdndistinct, stxddependencies, stxdmcv, stxdinherit +SELECT stxname, jsonb_pretty(d.stxdndistinct::text::jsonb) AS stxdndistinct, + jsonb_pretty(d.stxddependencies::text::jsonb) AS stxddependencies, stxdmcv, stxdinherit FROM pg_statistic_ext s LEFT JOIN pg_statistic_ext_data d ON (d.stxoid = s.oid) WHERE s.stxname = 'ab1_a_b_stats'; stxname | stxdndistinct | stxddependencies | stxdmcv | stxdinherit @@ -1433,10 +1434,48 @@ SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE CREATE STATISTICS func_deps_stat (dependencies) ON a, b, c FROM functional_dependencies; ANALYZE functional_dependencies; -- print the detected dependencies -SELECT dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; - dependencies ------------------------------------------------------------------------------------------------------------- - {"3 => 4": 1.000000, "3 => 6": 1.000000, "4 => 6": 1.000000, "3, 4 => 6": 1.000000, "3, 6 => 4": 1.000000} +SELECT jsonb_pretty(dependencies::text::jsonb) AS dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; + dependencies +----------------------------- + [ + + { + + "degree": 1.000000,+ + "attributes": [ + + 3 + + ], + + "dependency": 4 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + 3 + + ], + + "dependency": 6 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + 4 + + ], + + "dependency": 6 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + 3, + + 4 + + ], + + "dependency": 6 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + 3, + + 6 + + ], + + "dependency": 4 + + } + + ] (1 row) SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a = 1 AND b = ''1'''); @@ -1775,10 +1814,48 @@ SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE CREATE STATISTICS func_deps_stat (dependencies) ON (a * 2), upper(b), (c + 1) FROM functional_dependencies; ANALYZE functional_dependencies; -- print the detected dependencies -SELECT dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; - dependencies ------------------------------------------------------------------------------------------------------------------------- - {"-1 => -2": 1.000000, "-1 => -3": 1.000000, "-2 => -3": 1.000000, "-1, -2 => -3": 1.000000, "-1, -3 => -2": 1.000000} +SELECT jsonb_pretty(dependencies::text::jsonb) AS dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; + dependencies +----------------------------- + [ + + { + + "degree": 1.000000,+ + "attributes": [ + + -1 + + ], + + "dependency": -2 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + -1 + + ], + + "dependency": -3 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + -2 + + ], + + "dependency": -3 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + -1, + + -2 + + ], + + "dependency": -3 + + }, + + { + + "degree": 1.000000,+ + "attributes": [ + + -1, + + -3 + + ], + + "dependency": -2 + + } + + ] (1 row) SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a * 2) = 2 AND upper(b) = ''1'''); diff --git a/src/test/regress/sql/stats_ext.sql b/src/test/regress/sql/stats_ext.sql index 2c306dcc971d..e8aa6b580096 100644 --- a/src/test/regress/sql/stats_ext.sql +++ b/src/test/regress/sql/stats_ext.sql @@ -125,7 +125,8 @@ ALTER TABLE ab1 ALTER a SET STATISTICS -1; ALTER STATISTICS ab1_a_b_stats SET STATISTICS 0; \d ab1 ANALYZE ab1; -SELECT stxname, jsonb_pretty(d.stxdndistinct::text::jsonb) AS stxdndistinct, stxddependencies, stxdmcv, stxdinherit +SELECT stxname, jsonb_pretty(d.stxdndistinct::text::jsonb) AS stxdndistinct, + jsonb_pretty(d.stxddependencies::text::jsonb) AS stxddependencies, stxdmcv, stxdinherit FROM pg_statistic_ext s LEFT JOIN pg_statistic_ext_data d ON (d.stxoid = s.oid) WHERE s.stxname = 'ab1_a_b_stats'; ALTER STATISTICS ab1_a_b_stats SET STATISTICS -1; @@ -708,7 +709,7 @@ CREATE STATISTICS func_deps_stat (dependencies) ON a, b, c FROM functional_depen ANALYZE functional_dependencies; -- print the detected dependencies -SELECT dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; +SELECT jsonb_pretty(dependencies::text::jsonb) AS dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a = 1 AND b = ''1'''); @@ -844,7 +845,7 @@ CREATE STATISTICS func_deps_stat (dependencies) ON (a * 2), upper(b), (c + 1) FR ANALYZE functional_dependencies; -- print the detected dependencies -SELECT dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; +SELECT jsonb_pretty(dependencies::text::jsonb) AS dependencies FROM pg_stats_ext WHERE statistics_name = 'func_deps_stat'; SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a * 2) = 2 AND upper(b) = ''1'''); -- 2.51.0