The Prometheus monitoring system and time series database.

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beorn7 5b53aa1108 style: Replace `else if` cascades with `switch` Wiser coders than myself have come to the conclusion that a `switch` statement is almost always superior to a statement that includes any `else if`. The exceptions that I have found in our codebase are just these two: * The `if else` is followed by an additional statement before the next condition (separated by a `;`). * The whole thing is within a `for` loop and `break` statements are used. In this case, using `switch` would require tagging the `for` loop, which probably tips the balance. Why are `switch` statements more readable? For one, fewer curly braces. But more importantly, the conditions all have the same alignment, so the whole thing follows the natural flow of going down a list of conditions. With `else if`, in contrast, all conditions but the first are "hidden" behind `} else if `, harder to spot and (for no good reason) presented differently from the first condition. I'm sure the aforemention wise coders can list even more reasons. In any case, I like it so much that I have found myself recommending it in code reviews. I would like to make it a habit in our code base, without making it a hard requirement that we would test on the CI. But for that, there has to be a role model, so this commit eliminates all `if else` occurrences, unless it is autogenerated code or fits one of the exceptions above. Signed-off-by: beorn7 <beorn@grafana.com>		2 years ago
..
agent	style: Replace `else if` cascades with `switch`	2 years ago
chunkenc	style: Replace `else if` cascades with `switch`	2 years ago
chunks	style: Replace `else if` cascades with `switch`	2 years ago
docs	Merge branch 'main' into sparsehistogram	2 years ago
encoding	Merge 'main' into sparsehistogram	2 years ago
errors	Fix context.Canceled wrapping in compaction	2 years ago
fileutil	Update go to 1.19, set min version to 1.18 (#11279 )	2 years ago
goversion	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
index	style: Replace `else if` cascades with `switch`	2 years ago
record	tsdb: Add counter reset hint to histograms and support in WAL	2 years ago
testdata	tsdb: Delete blocks atomically; Remove tmp blocks on start; Added test. (#7772 )	4 years ago
tombstones	style: Replace `else if` cascades with `switch`	2 years ago
tsdbutil	Name float values as "floats", not as "values"	2 years ago
wlog	style: Replace `else if` cascades with `switch`	2 years ago
.gitignore	Moving tsdb into its own subdirectory	5 years ago
CHANGELOG.md	Rename default branch to main	4 years ago
README.md	Fixed broken link in tsdb README.md	2 years ago
block.go	tsdb: sort values for Postings only when required	2 years ago
block_test.go	Name float values as "floats", not as "values"	2 years ago
blockwriter.go	Merge 'main' into sparsehistogram	2 years ago
blockwriter_test.go	Name float values as "floats", not as "values"	2 years ago
compact.go	Rename PopulateBlockFunc to BlockPopulator	2 years ago
compact_test.go	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
db.go	style: Replace `else if` cascades with `switch`	2 years ago
db_test.go	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
example_test.go	storage: allow re-use of iterators	2 years ago
exemplar.go	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
exemplar_test.go	tsdb: in tests use labels.FromStrings	2 years ago
head.go	Making the number of CPU cores used for sorting postings lists editable (#12247 )	2 years ago
head_append.go	style: Replace `else if` cascades with `switch`	2 years ago
head_bench_test.go	Add out-of-order sample support to the TSDB (#11075 )	2 years ago
head_read.go	style: Replace `else if` cascades with `switch`	2 years ago
head_read_test.go	Fix merge conflicts	2 years ago
head_test.go	style: Replace `else if` cascades with `switch`	2 years ago
head_wal.go	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
isolation.go	tsdb: turn off transaction isolation for head compaction (#11317 )	2 years ago
isolation_test.go	tsdb: turn off transaction isolation for head compaction (#11317 )	2 years ago
mocks_test.go	Move packages out of deprecated pkg directory	3 years ago
ooo_head.go	Name float values as "floats", not as "values"	2 years ago
ooo_head_read.go	style: Replace `else if` cascades with `switch`	2 years ago
ooo_head_read_test.go	Name float values as "floats", not as "values"	2 years ago
ooo_head_test.go	Name float values as "floats", not as "values"	2 years ago
querier.go	style: Replace `else if` cascades with `switch`	2 years ago
querier_bench_test.go	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
querier_test.go	lint: Adjust to the lint warnings raised by current versions of golint-ci	2 years ago
repair.go	refactor: move from io/ioutil to io and os packages (#10528 )	3 years ago
repair_test.go	Simplify IndexReader.Series interface	2 years ago
tsdbblockutil.go	Support FloatHistogram in TSDB (#11522 )	2 years ago
wal.go	style: Replace `else if` cascades with `switch`	2 years ago
wal_test.go	TSDB: Rename wal package to wlog (#11352 )	2 years ago

README.md

TSDB

This directory contains the Prometheus TSDB (Time Series DataBase) library, which handles storage and querying of all Prometheus v2 data.

Documentation

External resources

A writeup of the original design can be found here.
Video: Storing 16 Bytes at Scale from PromCon 2017.
Compression is based on the Gorilla TSDB white paper.

A series of blog posts explaining different components of TSDB: