103 lines
2.5 KiB
MySQL
103 lines
2.5 KiB
MySQL
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-- UTF8 safe and lenght aware. Find a unique identifier with a given prefix
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-- and/or suffix and withing a schema.
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CREATE OR REPLACE FUNCTION cartodb.CDB_Unique_Identifier(prefix TEXT, relname TEXT, suffix TEXT, schema TEXT DEFAULT NULL)
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RETURNS TEXT
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AS $$
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DECLARE
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rec RECORD;
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usedspace INTEGER;
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ident TEXT;
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i INTEGER;
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origident TEXT;
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maxlen INTEGER;
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BEGIN
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maxlen := 63;
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usedspace := 3;
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usedspace := usedspace + coalesce(octet_length(prefix), 0);
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usedspace := usedspace + coalesce(octet_length(suffix), 0);
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relname := CDB_Octet_Trim(relname, usedspace + octet_length(relname) - maxlen);
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IF relname = '' THEN
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PERFORM _CDB_Error('prefixes are to long to generate a valid identifier', '_CDB_Unique_Identifier');
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END IF;
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ident := coalesce(prefix, '') || relname || coalesce(suffix, '');
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i := 0;
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origident := ident;
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WHILE i < 100 LOOP
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IF schema IS NOT NULL THEN
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SELECT c.relname, n.nspname
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INTO rec
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FROM pg_class c
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JOIN pg_namespace n ON c.relnamespace = n.oid
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WHERE c.relname = ident
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AND n.nspname = schema;
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ELSE
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SELECT c.relname, n.nspname
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INTO rec
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FROM pg_class c
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JOIN pg_namespace n ON c.relnamespace = n.oid
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WHERE c.relname = ident;
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END IF;
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IF NOT FOUND THEN
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RETURN ident;
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END IF;
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ident := origident || '_' || i;
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i := i + 1;
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END LOOP;
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PERFORM _CDB_Error('looping too far', '_CDB_Unique_Identifier');
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END;
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$$ LANGUAGE 'plpgsql';
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-- Trims the end of a given string by the given number of octets taking care
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-- not to leave characters in half. UTF8 safe.
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CREATE OR REPLACE FUNCTION cartodb.CDB_Octet_Trim(tostrip TEXT, octets INTEGER)
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RETURNS TEXT
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AS $$
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DECLARE
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expected INTEGER;
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examined INTEGER;
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tostriplen INTEGER;
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charlen INTEGER;
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i INTEGER;
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tail TEXT;
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trimmed TEXT;
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BEGIN
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charlen := bit_length('a');
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tostriplen := char_length(tostrip);
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expected := tostriplen * charlen;
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examined := bit_length(tostrip);
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IF expected = examined OR octets = 0 THEN
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RETURN SUBSTRING(tostrip from 1 for (tostriplen - octets));
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ELSIF octets < 0 THEN
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RETURN tostrip;
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ELSIF (octets * charlen) > examined THEN
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RETURN '';
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END IF;
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i := tostriplen - ((octets - 1) / 2);
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LOOP
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tail := SUBSTRING(tostrip from i for tostriplen);
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EXIT WHEN octet_length(tail) >= octets OR i <= 0;
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i := i - 1;
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END LOOP;
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trimmed := SUBSTRING(tostrip from 1 for (tostriplen - char_length(tail)));
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RETURN trimmed;
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END;
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$$ LANGUAGE 'plpgsql';
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