* Use single bit to differentiate between optimized bounds and floats
Use one bit to decide what kind of data to read/write.
This reduces storage need of floats from 72 bits to 65 bits and makes the
integers store in 5 to 32 bits instead of 16.
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
Signed-off-by: Jeanette Tan <jeanette.tan@grafana.com>
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
Signed-off-by: Jeanette Tan <jeanette.tan@grafana.com>
Signed-off-by: George Krajcsovits <krajorama@users.noreply.github.com>
Co-authored-by: Jeanette Tan <jeanette.tan@grafana.com>
* TSDB chunks: remove race between writing and reading
Because the data is stored as a bit-stream, the last byte in the stream
could change if the stream is appended to after an Iterator is obtained.
Copy the last byte when the Iterator is created, so we don't have to
read it later.
Clarify in comments that concurrent Iterator and Appender are allowed,
but the chunk must not be modified while an Iterator is created.
(This was already the case, in order to copy the bstream slice header.)
* TSDB: stop saving last 4 samples in memSeries
This extra copy of the last 4 samples was introduced to avoid a race
condition between reading the last byte of the chunk and writing to it.
But now we have fixed that by having `bstreamReader` copy the last byte,
we don't need to copy the last 4 samples.
This change saves 56 bytes per series, which is very worthwhile when
you have millions or tens of millions of series.
* TSDB: tidy up stopIterator re-use
Previous changes have left this code duplicating some lines; pull
them out to a separate function and tidy up.
* TSDB head_test: stop checking when iterators are wrapped
The behaviour has changed so chunk iterators are only wrapped when
transaction isolation requires them to stop short of the end.
This makes tests fail which are checking the type.
Tests should check the observable behaviour, not the type.
Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
* Fixed bstream test license
Signed-off-by: Marco Pracucci <marco@pracucci.com>
* Simplified bstreamReader.loadNextBuffer()
Signed-off-by: Marco Pracucci <marco@pracucci.com>
* Fixed date in license
Signed-off-by: Marco Pracucci <marco@pracucci.com>
This change also uses the latest staticcheck version which comes with
new verifications, hence some clean up in the code.
Signed-off-by: Simon Pasquier <spasquie@redhat.com>
This shows up as a hot spot in profiles of queries involving lots of seeks, as each seek creates a new iterator.
Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>
This replaces mutation of underlying bytes in the iterated slice
with a shift counter, which is used when reading the head byte.
This is avoids having to copy the entire slice for every new iterator.
xor encoding is fast enough for our purposes and provides
very good compression.
We remove all other ones that partially don't support floats
for the sake of simplicity.
Bryan Boreham