This INSERT operation performs a bulk insert. With partition level locking, the parser generates a static partition elimination list based on condition "PC = 4" (that is, positional matching of slppit1.pc = srct1.b = 4) and uses this list to place a PartitionRange lock.
The table definitions for this example are as follows:
CREATE TABLE HLSDS.SLPPIT1 (PI INT, PC INT, X INT) PRIMARY INDEX (PI) PARTITION BY (RANGE_N(PC BETWEEN 1 AND 100 EACH 10)); CREATE TABLE HLSDS.SRCT1 (A INT, B INT, C INT) PRIMARY INDEX (A);
An EXPLAIN of the INSERT operation shows the condition PC=4 as WHERE B=4:
Explain INSERT INTO HLSDS.SLPPIT1 SELECT A, B, C FROM HLSDS.SRCT1 WHERE B = 4; 1) First, we lock HLSDS.srct1 for read on a reserved RowHash to prevent global deadlock. 2) Next, we lock HLSDS.slppit1 for write on a reserved RowHash in a single partition to prevent global deadlock. 3) We lock HLSDS.srct1 for read, and we lock HLSDS.slppit1 for write on a single partition. 4) We do an all-AMPs RETRIEVE step from HLSDS.srct1 by way of an all-rows scan with a condition of ("HLSDS.srct1.b = 4") into Spool 1(all_amps), which is built locally on the AMPs. Then we do a SORT to partition Spool 1 by rowkey. The size of Spool 1 is estimated with no confidence to be 1 row (25 bytes). The estimated time for this step is 0.03 seconds. 5) We do an all-AMPs MERGE into HLSDS.slppit1 from Spool 1 (Last Use). The size is estimated with no confidence to be 1 row. The estimated time for this step is 0.55 seconds. 6) Finally, we send out an END TRANSACTION step to all AMPs involved in processing the request.