Query goal: | Find base table columns in case of which the system can use TOAST technique (due to the data type of the column) and where the toasting strategy has been changed so that it is different than the default strategy determined by the type. Make sure that the new strategy is optimal. |
Notes about the query: | Explanation of the toasting strategy.
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Query type: | General (Overview of some aspect of the database.) |
Query license: | MIT License |
Data source: | system catalog only |
SQL query: | Click on query to copy it
SELECT n.nspname AS table_schema, c.relname AS table_name, at.attname AS column_name, tp.typname AS column_data_type_name, tbt.typname AS column_base_data_type_name, CASE WHEN tp.typstorage='p' THEN 'plain' WHEN tp.typstorage='e' THEN 'external' WHEN tp.typstorage='m' THEN 'main' WHEN tp.typstorage='x' THEN 'extended' END AS type_toasting_strategy, CASE WHEN at.attstorage ='p' THEN 'plain' WHEN at.attstorage='e' THEN 'external' WHEN at.attstorage='m' THEN 'main' WHEN at.attstorage='x' THEN 'extended' END AS column_toasting_strategy FROM pg_attribute at INNER JOIN pg_class c ON at.attrelid=c.oid INNER JOIN pg_namespace AS n ON n.oid=c.relnamespace INNER JOIN pg_authid AS a ON n.nspowner=a.oid INNER JOIN pg_type AS tp ON at.atttypid=tp.oid LEFT JOIN pg_type AS tbt ON tp.typbasetype=tbt.oid WHERE (nspname='public' OR rolname<>'postgres') AND c.relkind IN ('r') AND at.attisdropped='f' AND at.attnum>0 AND tp.typlen = -1 AND tp.typstorage<>at.attstorage ORDER BY table_schema, table_name, at.attnum; |
Collection name | Collection description |
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Find problems by overview | Queries that results point to different aspects of database that might have problems. A human reviewer has to decide based on the results as to whether there are problems or not . |
Category name | Category description |
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Data at the database physical level | Queries of this category provide information about the disk usage. |
TOAST | Queries of this category provide information about The Oversized-Attribute Storage Technique. |
Reference |
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https://postgrespro.com/docs/postgrespro/current/storage-toast |
https://wiki.postgresql.org/wiki/TOAST |
https://www.postgresql.org/docs/current/storage-toast.html |