Edge case for zero ordering value

Common case of comparing zero ordering value is: delete block contain 0 as the ordering value, and the base record has , say 100, as the ordering. The ordering value will be ignored, commit time will be used for order comparison.

An ordering value of a delete log block could be non-zero, say 100, and the existing ordering (from update data block or the base file) of the record could be 0. Currently, we treat the delete having higher order, thus delete the record.

For aligning on the semantic of treating 0 ordering value, should the 0 value from existing records be also treated as non-comparable, and fall back to commit time ordering?

No file, test, or entry point is named. Start by locating the ordering comparison for delete log blocks and existing records; done means zero ordering values fall back to commit-time comparison consistently.

Written by the indexing model from the issue text.