Bug 57884

Summary: XSSFDataFormat.getFormat is slow with large numbers of formats
Product: POI Reporter: Nick Burch <apache>
Component: XSSFAssignee: POI Developers List <dev>
Status: NEW ---    
Severity: enhancement    
Priority: P2    
Version: 3.12-dev   
Target Milestone: ---   
Hardware: PC   
OS: Linux   
Bug Depends on: 57880    
Bug Blocks:    

Description Nick Burch 2015-05-03 07:36:08 UTC
As discovered when working on #57880, for XSSF, creating 33,000 cell styles is 30 times faster than creating the same number of format indexes. For 5,000 cell styles and formats, creating the cell styles is only 3 times faster than creating the formats.
Comment 1 Nick Burch 2015-05-03 07:54:08 UTC
In r1677368 I've made a few changes which gives a 3x speed improvement on creating 33,000 data formats in XSSF. It's still slower to create the formats than it is to create cell styles, so there may be some more optimisations to do