[HAWQ-944] Numutils.c: pg_ltoa and pg_itoa functions allocate unnecessary amount of bytes

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.2.0.0-incubating
• Component/s: Core
• Assignee: Kavinder Dhaliwal
• Reporter: Kavinder Dhaliwal
• Created: 21/Jul/16 16:19
• Updated: 24/Feb/17 17:29
• Resolved: 24/Feb/17 17:29

Description

The current implementations of pg_ltoa and pg_itoa allocate a 33 byte char array and set the input pointer to that array. This is far too many bytes than needed to translate an int16 or int32 to a string

int32 -> 10 bytes maximum + 1 sign bit + '\0' = 12 bytes
int16 -> 5 bytes maximum + 1 sign bit + '\0' = 7 bytes

When HAWQ/Greenplum forked from Postgres the two functions simply delegated to sprintf so an optimization was introduced that involved the 33 byte solution. Postgres itself implemented these functions in commit https://github.com/postgres/postgres/commit/4fc115b2e981f8c63165ca86a23215380a3fda66 that require a 12 byte maximum char pointer.

This is a minor improvement that can be made to the HAWQ codebase and it's relatively little effort to do so.

Issue Links

• links to: GitHub Pull Request #808