55 lines
1.3 KiB
PL/PgSQL
55 lines
1.3 KiB
PL/PgSQL
-- Return an array of table names scanned by a given query
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--
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-- Requires PostgreSQL 9.x+
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--
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CREATE OR REPLACE FUNCTION CDB_QueryTables(query text)
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RETURNS name[]
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AS $$
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DECLARE
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exp XML;
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tables NAME[];
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rec RECORD;
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rec2 RECORD;
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BEGIN
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tables := '{}';
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FOR rec IN SELECT CDB_QueryStatements(query) q LOOP
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BEGIN
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EXECUTE 'EXPLAIN (FORMAT XML) ' || rec.q INTO STRICT exp;
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EXCEPTION WHEN others THEN
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RAISE WARNING 'Cannot explain query: % (%)', rec.q, SQLERRM;
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CONTINUE;
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END;
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-- Now need to extract all values of <Relation-Name>
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--RAISE DEBUG 'Explain: %', exp;
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FOR rec2 IN WITH
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inp AS ( SELECT xpath('//x:Relation-Name/text()', exp, ARRAY[ARRAY['x', 'http://www.postgresql.org/2009/explain']]) as x )
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SELECT unnest(x)::name as p from inp
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LOOP
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--RAISE DEBUG 'tab: %', rec2.p;
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tables := array_append(tables, rec2.p);
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END LOOP;
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-- RAISE DEBUG 'Tables: %', tables;
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END LOOP;
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-- RAISE DEBUG 'Tables: %', tables;
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-- Remove duplicates and sort by name
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IF array_upper(tables, 1) > 0 THEN
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WITH dist as ( SELECT DISTINCT unnest(tables)::text as p ORDER BY p )
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SELECT array_agg(p) from dist into tables;
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END IF;
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--RAISE DEBUG 'Tables: %', tables;
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return tables;
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END
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$$ LANGUAGE 'plpgsql' VOLATILE STRICT;
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