dictionary size soft limit
Nobody has claimed this yet.
Assessment
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Newbie friendliness
- 67/100
- Issue type
- Documentation
- Clarity
- Mostly clear
- Activity status
- Active
- Tech stack
- lua
- Domain
- documentation
Research direction
The issue describes dictionary column degradation and how it appears in index:info(), but names no documentation file. Start by locating the existing documentation for dictionary indexes and index:info(); check how it explains column limits and degradation. Done when that documentation explains when degradation happens, its effect on storage and scans, and how to inspect the degradation field.
Written by the indexing model from the issue text.
Description
Now on attempt to insert (replace etc) a value that does not fit into
already full dictionary column becomes degraded. In this mode we convert
a block from dictionary layout to layout with plain strings before
mutating a block.
Degraded column is still scanned using dictionary layout, but in this
case dictionary is built per scan.
Degraded column mode is introduced for technical reasons. It is not
recommended to operate in this mode. Such column will become eventually
more or less same as column with plain strings in terms of memory
consumption and performance.
Whether column is degraded is visible in index:info():
tarantool> index:info().columns.<name>.degradation
---
- dictionary overflow
...
...
The field is nil for dictionary column without degradation or
non-dictionary column.
Requested by @nshy in https://github.com/tarantool/tarantool-ee/commit/b01e5649f49d5378d7e85fa11bc0c82058b5ec1e.
- Dominant language
- CSS
- Stars
- 16
- Forks
- 49
- Avg merge
- 5d 18h
- Merged PRs (30d)
- 1
Getting set up
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