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Set columns to null instead of dropping to avoid pg_deadlock during updates (#1710)

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This PR addresses a pg_deadlock error that would cause an update to fail if a `select getmvt` was queried during update. The deadlock occurred due to an ALTER TABLE DROP COLUMN operation on temporary columns  ( `new_source_ids` and `old_source_ids`) in some linestring tables.

**Changes:**
*  instead of adding/dropping the columns during update, they are now updated and set to NULL. 
* Added new indexes on the source_ids columns  to speed up the UPDATE. 
* Will refresh `osm_park_polygon_dissolve_z4` concurrently in `park_polygon.refresh()` to avoid blocking. 

Co-authored-by: Patrik Sylve <patrik.sylve@t-kartor.com>
This commit is contained in:
Patrik Sylve
2025-02-28 13:27:52 +01:00
committed by GitHub
parent e6a1000155
commit f70ae783b2
4 changed files with 65 additions and 44 deletions
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23
layers/waterway/update_important_waterway.sql
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@@ -21,6 +21,8 @@ CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring (
id SERIAL,
geometry geometry('LineString'),
source_ids bigint[],
new_source_ids bigint[],
old_source_ids bigint[],
name varchar,
name_en varchar,
name_de varchar,
@@ -28,6 +30,15 @@ CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring (
);
ALTER TABLE osm_important_waterway_linestring ADD COLUMN IF NOT EXISTS source_ids bigint[];
-- Create temporary Merged-LineString to Source-LineStrings-ID columns to store relations before they have been
-- intersected
ALTER TABLE osm_important_waterway_linestring ADD COLUMN IF NOT EXISTS new_source_ids BIGINT[];
ALTER TABLE osm_important_waterway_linestring ADD COLUMN IF NOT EXISTS old_source_ids BIGINT[];
CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_n_source_ids_not_null_idx
ON osm_important_waterway_linestring ((new_source_ids IS NOT NULL));
CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_o_source_ids_not_null_idx
ON osm_important_waterway_linestring ((old_source_ids IS NOT NULL));
-- Create osm_important_waterway_linestring_gen_z11 as a copy of osm_important_waterway_linestring but drop the
-- "source_ids" column. This can be done because z10 and z9 tables are only simplified and not merged, therefore
@@ -35,6 +46,8 @@ ALTER TABLE osm_important_waterway_linestring ADD COLUMN IF NOT EXISTS source_id
CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring_gen_z11
(LIKE osm_important_waterway_linestring);
ALTER TABLE osm_important_waterway_linestring_gen_z11 DROP COLUMN IF EXISTS source_ids;
ALTER TABLE osm_important_waterway_linestring_gen_z11 DROP COLUMN IF EXISTS new_source_ids;
ALTER TABLE osm_important_waterway_linestring_gen_z11 DROP COLUMN IF EXISTS old_source_ids;
-- Create osm_important_waterway_linestring_gen_z10 as a copy of osm_important_waterway_linestring_gen_z11
CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring_gen_z10
@@ -478,10 +491,6 @@ BEGIN
CREATE INDEX ON clustered_linestrings_to_merge (cluster_group, cluster);
ANALYZE clustered_linestrings_to_merge;
-- Create temporary Merged-LineString to Source-LineStrings-ID columns to store relations before they have been
-- intersected
ALTER TABLE osm_important_waterway_linestring ADD COLUMN IF NOT EXISTS new_source_ids BIGINT[];
ALTER TABLE osm_important_waterway_linestring ADD COLUMN IF NOT EXISTS old_source_ids BIGINT[];
WITH inserted_linestrings AS (
-- Merge LineStrings of each cluster and insert them
@@ -527,9 +536,9 @@ BEGIN
-- Cleanup remaining table
DROP TABLE clustered_linestrings_to_merge;
-- Drop temporary Merged-LineString to Source-LineStrings-ID columns
ALTER TABLE osm_important_waterway_linestring DROP COLUMN IF EXISTS new_source_ids;
ALTER TABLE osm_important_waterway_linestring DROP COLUMN IF EXISTS old_source_ids;
-- Restore temporary Merged-LineString to Source-LineStrings-ID columns
UPDATE osm_important_waterway_linestring SET new_source_ids = NULL WHERE new_source_ids IS NOT NULL;
UPDATE osm_important_waterway_linestring SET old_source_ids = NULL WHERE old_source_ids IS NOT NULL;
-- noinspection SqlWithoutWhere
DELETE FROM waterway_important.changes;