DBF import performance

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dbf-import-perfHere is another performance win! Importing dbf files into Calc is now quicker by 80%. You will probably notice the difference especially when importing a large dbf file. The test document I used had roughly 24000 rows, and importing that took 57 seconds on my machine. Having 24000 rows in a database file (or even in a spreadsheet file) is very common by today’s standard, so this wasn’t good at all.

I had done quite a bit of performance work over the years, but this one was somewhat difficult to tackle. The bottlenecks were fragmented all over the place which required different solutions to different areas. Roughly speaking, the following are the areas I tackled to reduce the total import time for dbf files (module name in parentheses):

  • speedup in parsing of dbf file content (connectivity)
  • disabled property change notification during dbf import (dbaccess)
  • more efficient string interning and unicode conversion (sal)
  • reduction in column array re-allocation during import (sc)
  • removal of unnecessary column and row size adjustments post-import (sc)

With all of this, the file that originally took 57 seconds to load now loads in 12 seconds on the same hardware, which roughly translates to 80% reduction of the total import time!

This itself is pretty impressive; however, I was hoping to get it at least under 10 seconds since Excel can load the same file less than 5 seconds on the same hardware, even through wine emulation (!). But that’s probably for a future project. For now, I’m content with what I’ve done.