Optimizer Trace: save all info needed for replay

Optimizer trace contains a lot of info describing the query:

• Original query text
• Definitions of all used VIEWs
• All kinds of estimates that the optimizer used:
  • records_in_range estimates
  • index statistics used by
  • selectivity estimates
  • table read costs
• Indexes considered by the optimizer

This makes it possible to debug an optimizer problem: re-run the optimizer and manually re-create the environment by "faking" the record counts and the estimates.

There are two problems

• 1. Optimizer trace is not fully self-contained.
• 2. Re-creating the environment is labor-intensive (I wrote dirty patches that put the fake statistics in place)

This task is about solving #1, and possibly #2.

For #1, we need:

• Column definitions (their datatypes. Basically, SQL definitions).
• TODO: anything else?