This should improve performance when blockSearch.getColumnsHeader() is called multiple times
from different places of the code.
(cherry picked from commit 9e48074b59)
This improves performance for analytical queries, which do not need column headers metadata.
For example, the following query doesn't need column headers metadata, since _stream and min(_time)
are stored in block header, which is read separately from colum headers metadata:
_time:1w | stats by (_stream) min(_time) min_time
This commit significantly improves the performance for this query.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7070
Substitute global streamTagsCache with per-blockSearch cache for ((stream.id) -> (_stream value)) entries.
This improves scalability of obtaining _stream values on a machine with many CPU cores, since every CPU
has its own blockSearch instance.
This also should reduce memory usage when querying logs over big number of streams, since per-blockSearch
cache of ((stream.id) -> (_stream value)) entries is limited in size, and its lifetime is bounded by a single query.
