[JENA-28] Drop Temporary Tables in Postgres (PATCH)

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Won't Fix
• Component/s: SDB

Environment

Effects SDB PostgreSQL

• Assignee: Damian Steer
• Reporter: Gavin Carothers
• Created: 12/Jan/11 22:30
• Updated: 07/Jul/17 23:53
• Resolved: 07/Jul/17 23:53

Description

Current behaviour to truncate the temporary tables leaves the table objects, and thanks to MVCC in Postgres the data in those tables around for far longer then expected. This causes HUGE write loads on the database when loading a large number of quads or triples transactionally.

Fix is VERY simple:

Index: src/com/hp/hpl/jena/sdb/layout2/hash/TupleLoaderHashPGSQL.java
===================================================================
— src/com/hp/hpl/jena/sdb/layout2/hash/TupleLoaderHashPGSQL.java (revision 8420)
+++ src/com/hp/hpl/jena/sdb/layout2/hash/TupleLoaderHashPGSQL.java (working copy)
@@ -26,7 +26,7 @@
}

public String[] getCreateTempTable() {

• return new String[] { "CREATE TEMPORARY TABLE" , "ON COMMIT DELETE ROWS" }

  ;
  + return new String[]

  { "CREATE TEMPORARY TABLE" , "ON COMMIT DROP" }

  ;
  }