This adds negative buckets and access of float histograms to
TestHistogramChunkSameBuckets and TestHistogramChunkBucketChanges.
It also exercises a specific pattern of reusing an iterator (one where
no access has happened).
This exposes two bugs (where entries for positive buckets where used
where the corresponding entries for negative buckets should have been
used). One was fixed in #11627 (not merged), which triggered the work
in this commit.
This commit fixes both issues, so #11627 can be closed.
It also simplifies the code in the histogramIterator.Next method that
aims to recycle existing slice capacity.
Furthermore, this is on top of the release-2.40 branch because we
should probably cut a bugfix release for this.
Signed-off-by: beorn7 <beorn@grafana.com>
With these changes, the "happy path" when the leading and trailing
number of bits don't need an update, fewer operations are needed.
The change is probably very marginal (no change in the benchmark added
here, but the benchmark also doesn't cover non-changing values), and
an argument could me made that avoiding pointers also has its
benefits.
However, I think that reducing the number of return values improves
readability. Which convinced me that I should at least propose this.
Signed-off-by: beorn7 <beorn@grafana.com>
Previously, the maxTime wasn't updated properly in case of a recoding
happening.
My apologies for reformatting many lines for line length. During the
bug hunt, I tried to make things more readable in a reasonably wide
editor window.
Signed-off-by: beorn7 <beorn@grafana.com>
- Pick At... method via return value of Next/Seek.
- Do not clobber returned buckets.
- Add partial FloatHistogram suppert.
Note that the promql package is now _only_ dealing with
FloatHistograms, following the idea that PromQL only knows float
values.
As a byproduct, I have removed the histogramSeries metric. In my
understanding, series can have both float and histogram samples, so
that metric doesn't make sense anymore.
As another byproduct, I have converged the sampleBuf and the
histogramSampleBuf in memSeries into one. The sample type stored in
the sampleBuf has been extended to also contain histograms even before
this commit.
Signed-off-by: beorn7 <beorn@grafana.com>
This is to avoid copying the many fields of a histogram.Histogram all
the time.
This also fixes a bunch of formerly broken tests.
Signed-off-by: beorn7 <beorn@grafana.com>
This adds bit buckets for larger numbers to varbit encoding and also
an unsigned version of varbit encoding.
Then, varbit encoding is used for all the histogram chunk data instead
of varint.
Signed-off-by: beorn7 <beorn@grafana.com>
A lot of this code was hacked together, literally during a
hackathon. This commit intends not to change the code substantially,
but just make the code obey the usual style practices.
A (possibly incomplete) list of areas:
* Generally address linter warnings.
* The `pgk` directory is deprecated as per dev-summit. No new packages should
be added to it. I moved the new `pkg/histogram` package to `model`
anticipating what's proposed in #9478.
* Make the naming of the Sparse Histogram more consistent. Including
abbreviations, there were just too many names for it: SparseHistogram,
Histogram, Histo, hist, his, shs, h. The idea is to call it "Histogram" in
general. Only add "Sparse" if it is needed to avoid confusion with
conventional Histograms (which is rare because the TSDB really has no notion
of conventional Histograms). Use abbreviations only in local scope, and then
really abbreviate (not just removing three out of seven letters like in
"Histo"). This is in the spirit of
https://github.com/golang/go/wiki/CodeReviewComments#variable-names
* Several other minor name changes.
* A lot of formatting of doc comments. For one, following
https://github.com/golang/go/wiki/CodeReviewComments#comment-sentences
, but also layout question, anticipating how things will look like
when rendered by `godoc` (even where `godoc` doesn't render them
right now because they are for unexported types or not a doc comment
at all but just a normal code comment - consistency is queen!).
* Re-enabled `TestQueryLog` and `TestEndopints` (they pass now,
leaving them disabled was presumably an oversight).
* Bucket iterator for histogram.Histogram is now created with a
method.
* HistogramChunk.iterator now allows iterator recycling. (I think
@dieterbe only commented it out because he was confused by the
question in the comment.)
* HistogramAppender.Append panics now because we decided to treat
staleness marker differently.
Signed-off-by: beorn7 <beorn@grafana.com>
