LP#1419172 Optimize full_circ_count view to avoid seq scans

As reported by Chris Sharp:

"The reporter.classic_item_list view was modified in bug 1208572 to use
extend_reporter.full_circ_count to provide the use count for each item.
Unfortunately, this change was found to be the cause of consistently
long-running (2+ hours) reports queries in PINES as its query plan on
our PostgreSQL 9.3 server was resulting in sequential scans of both the
circulation and aged_circulation tables."

This commit restructures the view to avoid JOINs, and is in production
at PINES with noted improvement.

Signed-off-by: Dan Wells <dbw2@calvin.edu>

diff --git a/Open-ILS/src/sql/Pg/extend-reporter.sql b/Open-ILS/src/sql/Pg/extend-reporter.sql
index cb7eec5..852b537 100644 (file)
--- a/Open-ILS/src/sql/Pg/extend-reporter.sql
+++ b/Open-ILS/src/sql/Pg/extend-reporter.sql
@@ -26,12 +26,11 @@ CREATE TABLE extend_reporter.legacy_circ_count (
 );
 
 CREATE OR REPLACE VIEW extend_reporter.full_circ_count AS
- SELECT cp.id, COALESCE(c.circ_count, 0::bigint) + COALESCE(count(DISTINCT circ.id), 0::bigint) + COALESCE(count(DISTINCT acirc.id), 0::bigint) AS circ_count
-   FROM asset."copy" cp
-   LEFT JOIN extend_reporter.legacy_circ_count c USING (id)
-   LEFT JOIN "action".circulation circ ON circ.target_copy = cp.id
-   LEFT JOIN "action".aged_circulation acirc ON acirc.target_copy = cp.id
-  GROUP BY cp.id, c.circ_count;
+   SELECT cp.id,
+   COALESCE((SELECT circ_count FROM extend_reporter.legacy_circ_count WHERE id = cp.id), 0)
+   + (SELECT COUNT(*) FROM action.circulation WHERE target_copy = cp.id)
+   + (SELECT COUNT(*) FROM action.aged_circulation WHERE target_copy = cp.id) AS circ_count
+   FROM asset.copy cp;
 
 CREATE OR REPLACE VIEW extend_reporter.global_bibs_by_holding_update AS
   SELECT DISTINCT ON (id) id, holding_update, update_type

diff --git a/Open-ILS/src/sql/Pg/upgrade/XXXX.schema.optimize_full_circ_count.sql b/Open-ILS/src/sql/Pg/upgrade/XXXX.schema.optimize_full_circ_count.sql
new file mode 100644 (file)
index 0000000..6440dfa
--- /dev/null
+++ b/Open-ILS/src/sql/Pg/upgrade/XXXX.schema.optimize_full_circ_count.sql
@@ -0,0 +1,12 @@
+BEGIN;
+
+SELECT evergreen.upgrade_deps_block_check('XXXX', :eg_version);
+
+CREATE OR REPLACE VIEW extend_reporter.full_circ_count AS
+   SELECT cp.id,
+   COALESCE((SELECT circ_count FROM extend_reporter.legacy_circ_count WHERE id = cp.id), 0)
+   + (SELECT COUNT(*) FROM action.circulation WHERE target_copy = cp.id)
+   + (SELECT COUNT(*) FROM action.aged_circulation WHERE target_copy = cp.id) AS circ_count
+   FROM asset.copy cp;
+
+COMMIT;