* Test for a previous implematation of Intersect
Before we were moving the postings list everytime we create a new
chained `intersectPostings`. That was causing some postings to be
skipped. This test fails on the older version.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Advance on Seek only when valid.
Issue:
Before in mergedPostings and others we advance everytime we `Seek`,
which causes issues with `Intersect`.
Take the case, where we have a mergedPostings = m merging, a: {10, 20, 30} and
b: {15, 25, 35}. Everytime we `Seek`, we do a.Seek and b.Seek.
Now if we Intersect m with {21, 22, 23, 30}, we would do Seek({21,22,23}) which
would advance a and b beyond 30.
Fix:
Now we advance only when the seeking value is greater than the current
value, as the definition specifies.
Also, posting 0 will not be a valid posting and will be used to signal
finished or un-initialized PostingsList.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Add test for Merge+Intersect edgecase.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
* Add comments to trivial tests.
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
NaN != NaN, so the previous code would incorrectly report
it as changed.
There's also plans to take advantage of the NaN payload,
so look at the entire value.
When calling AddFast, we check the details of the head chunk of the
referred memorySeries. But it could happen that there are no chunks in
the series at all.
Currently, we are deferring chunk creation to when we actually append
samples, but we can be sure that there will be samples if the series is
created. We will be consuming no extra memory by cutting a chunk when we
create the series.
Ref: #28 comment 2
Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>
This adds a workaround to avoid deadlocks for inconsistent write lock
order across headBlocks.
Things keep working if transactions only append data for the same
timestamp, which is generally the case for Prometheus.
Full behavior should be restored in a subsequent change.
The compilation and tests are broken as head.go requires sample which
has been moved to another package while moving BufferedSeriesIterator.
Duplication seemed better compared to exposing sample from tsdbutil.
This fixes different race condition encoutnered when running Prometheus.
It reduces the overall performance in the synthetic benchmark a fair bit
but has no indiciations of impacting a real-world setup notably.
This adds the Queryable interface to the Block interface. Head and
persisted blocks now implement their own Querier() method and thus
isolate customization (e.g. remapPostings) more cleanly.
This adds more lower-leve interfaces which are used to compose
to different Block interfaces.
The DB only uses interfaces instead of explicit persistedBlock and
headBlock. The headBlock generation property is dropped as the use-case
can be implemented using block sequence numbers.
The position mapper was intended to pre-computed "expensive" ordering
of label sets. It was expensive to update and caused a lot of trouble.
Skipping this optimization entirely actually revelead it was pointless
and even harmful from the e2e perspective.
This adds handling for various corruption scenarios of the WAL.
If corruption is encountered, we truncate the WAL after the last valid
entry transparently and continue appending after the offset.
This has been a common source of hard to debug issues. Its a premature
and unbenchmarked optimization and semantically, we want ChunkMetas to
be references in all changed cases.
This fixes a bug where the last WAL file was closed after consuming it
instead of being left open for further writes.
Reloading of blocks on startup considers loading head blocks now.
Introduce a seperate mutex for the head blocks to avoid a race where
a post-compaction reload may run between switching the DB's base mutex
to create a new head block in an appender.
This adds write path support for segmented chunk data files.
Files of 512MB are pre-allocated and written to. If the file size
is exceeded, the next file is started. On completion, files
are truncated to their final size.
This is an initial (and hacky) first pass on allowing
appending to multiple blocks simultaniously to avoid
dropping samples right after cutting a new head block.
It's also required for cases like the PGW, where a scrape may
contain varying timestamps.
