How do I speed up zigzag merge on development server?

Question

I am just starting to take advantage of zigzag merge to reduce # of indexes, and am testing on my dev machine. I am finding it to be extremely slow, even when the # of results in each query is not large.

For example: 1) one query with 25 results takes ~5 seconds 2) two queries with 25 results each, and 25 merged takes 15 seconds 3) three queries with 25 results each, and 1 merged takes 100 seconds!

Is this expected???

Answer 1

This is currently a bug in the development server. A change was made to make some merge joins faster, but unfortunately made other ones significantly slower. There is an issue tracking this bug here. I would recommend using the 1.9.2 dev appserver for testing until this is fixed, or if you feel comfortable update the development server code as seen in the issue.