PolarDB:Use global partitioned index scan in DML operations

Usage

• Create a partitioned table and a global partitioned index:

  CREATE TABLE gi_ora
  (
      a int,
      b int,
      c int GENERATED ALWAYS AS (b * 2),
      d int DEFAULT 0,
      e int,
      f text,
      g text
  ) PARTITION BY RANGE (a)
  (
      partition p0 values less than (50),
      partition p1 values less than (100),
      partition p2 values less than (200),
      partition p3 values less than (300),
      partition p4 values less than (400),
      partition p5 values less than (500),
      partition p6 values less than (600),
      partition p7 values less than (700),
      partition p8 values less than (800)
  );
  
  INSERT INTO gi_ora(a,b,d,e,f,g) SELECT i,i,i, (random()*1000)::int,(random()*30000000)::int::text,(random()*30000000)::int::text FROM generate_series(1,799) i ;
  
  CREATE INDEX ON gi_ora(b) global PARTITION BY RANGE (b)
  (
      partition gpi_p0 values less than (500),
      partition gpi_p1  values less than (maxvalue)
  );
  ANALYZE gi_ora;

• Use global partitioned index scan in the DELETE operation on specified data:

  EXPLAIN (costs off, verbose on)  DELETE FROM gi_ora WHERE b = 198;

  Sample result:

                                        QUERY PLAN
  ---------------------------------------------------------------------------------------
   DELETE ON public.gi_ora
     ->  GLOBAL PARTITIONED INDEX SCAN(1/2) USING gi_ora_b_tableoid_idx ON public.gi_ora
           Output: gi_ora.tableoid, gi_ora.ctid
           Index Cond: (gi_ora.b = 198)
  (4 rows)

• Use global partitioned index scan in the UPDATE operation on specified data:

  EXPLAIN (costs off, verbose on)  UPDATE gi_ora SET a = a - 10 WHERE b = 198;

  Sample result:

                                        QUERY PLAN
  ---------------------------------------------------------------------------------------
   UPDATE ON public.gi_ora
     ->  GLOBAL PARTITIONED INDEX SCAN(1/2) USING gi_ora_b_tableoid_idx ON public.gi_ora
           Output: (gi_ora.a - 10), gi_ora.tableoid, gi_ora.ctid
           Index Cond: (gi_ora.b = 198)
  (4 rows)