With this change we now provide a check for new IDs for overflow. This
will cause the system to panic on overflow now rather than causing
silent corruption as this is an unrecoverable state. While this is a
highly unlikely scenario given how big the id numbers can be, it would
be better to have this in place now, rather than trying to figure out
a subtle nasty corruption bug later.
Closes#25542
Closes#25461
_Note: the first three commits on this PR are from https://github.com/influxdata/influxdb/pull/25492_
This PR makes the switch from using names for columns to the use of `ColumnId`s. Where column names are used, they are represented as `Arc<str>`. This impacts most components of the system, and the result is a fairly sizeable change set. The area where the most refactoring was needed was in the last-n-value cache.
One of the themes of this PR is to rely less on the arrow `Schema` for handling the column-level information, and tracking that info in our own `ColumnDefinition` type, which captures the `ColumnId`.
I will summarize the various changes in the PR below, and also leave some comments in-line in the PR.
## Switch to `u32` for `ColumnId`
The `ColumnId` now follows the `DbId` and `TableId`, and uses a globally unique `u32` to identify all columns in the database. This was a change from using a `u16` that was only unique within the column's table. This makes it easier to follow the patterns used for creating the other identifier types when dealing with columns, and should reduce the burden of having to manage the state of a table-scoped identifier.
## Changes in the WAL/Catalog
* `WriteBatch` now contains no names for tables or columns and purely uses IDs
* This PR relies on `IndexMap` for `_Id`-keyed maps so that the order of elements in the map is consistent. This has important implications, namely, that when iterating over an ID map, the elements therein will always be produced in the same order which allows us to make assertions on column order in a lot of our tests, and allows for the re-introduction of `insta` snapshots for serialization tests. This map type provides O(1) lookups, but also provides _fast_ iteration, which should help when serializing these maps in write batches to the WAL.
* Removed the need to serialize the bi-directional maps for `DatabaseSchema`/`TableDefinition` via use of `SerdeVecMap` (see comments in-line)
* The `tables` map in `DatabaseSchema` no stores an `Arc<TableDefinition>` so that the table definition can be shared around more easily. This meant that changes to tables in the catalog need to do a clone, but we were already having to do a clone for changes to the DB schema.
* Removal of the `TableSchema` type and consolidation of its parts/functions directly onto `TableDefinition`
* Added the `ColumnDefinition` type, which represents all we need to know about a column, and is used in place of the Arrow `Schema` for column-level meta-info. We were previously relying heavily on the `Schema` for iterating over columns, accessing data types, etc., but this gives us an API that we have more control over for our needs. The `Schema` is still held at the `TableDefinition` level, as it is needed for the query path, and is maintained to be consistent with what is contained in the `ColumnDefinition`s for a table.
## Changes in the Last-N-Value Cache
* There is a bigger distinction between caches that have an explicit set of value columns, and those that accept new fields. The former should be more performant.
* The Arrow `Schema` is managed differently now: it used to be updated more than it needed to be, and now is only updated when a row with new fields is pushed to a cache that accepts new fields.
## Changes in the write-path
* When ingesting, during validation, field names are qualified to their associated column ID
This PR introduces a new type `SerdeVecHashMap` that can be used in places where we need a HashMap with the following properties:
1. When serialized, it is serialized as a list of key-value pairs, instead of a map
2. When deserialized, it assumes the serialization format from (1.) and deserializes from a list of key-value pairs to a map
3. Does not allow for duplicate keys on deserialization
This is useful in places where we need to create map types that map from an identifier (integer) to some value, and need to serialize that data. For example: in the WAL when serializing write batches, and in the catalog when serializing the database/table schema.
This PR refactors the code in `influxdb3_wal` and `influxdb3_catalog` to use the new type for maps that use `DbId` and `TableId` as the key. Follow on work can give the same treatment to `ColumnId` based maps once that is fully worked out.
## Explanation
If we have a `HashMap<u32, String>`, `serde_json` will serialize it in the following way:
```json
{"0": "foo", "1": "bar"}
```
i.e., the integer keys are serialized as strings, since JSON doesn't support any other type of key in maps.
`SerdeVecHashMap<u32, String>` will be serialized by `serde_json` in the following way:
```json,
[[0, "foo"], [1, "bar"]]
```
and will deserialize from that vector-based structure back to the map. This allows serialization/deserialization to run directly off of the `HashMap`'s `Iterator`/`FromIterator` implementations.
## The Controversial Part
One thing I also did in this PR was switch the catalog from using a `BTreeMap` for tables to using the new `HashMap` type. This breaks the deterministic ordering of the database schema's `tables` map and therefore wrecks the snapshot tests we were using. I had to comment those parts of their respective tests out, because there isn't an easy way to make the underlying hashmap have a deterministic ordering just in tests that I am aware of.
If we think that using `BTreeMap` in the catalog is okay over a `HashMap`, then I think it would be okay to roll a similar `SerdeVecBTreeMap` type specifically for the catalog. Coincidentally, this may actually be a good use case for [`indexmap`](https://docs.rs/indexmap/latest/indexmap/), since it holds supposedly similar lookup performance characteristics to hashmap, while preserving order and _having faster iteration_ which could be a win for WAL serialization speed. It also accepts different hashing algorithms so could be swapped in with FNV like `HashMap` can.
## Follow-up work
Use the `SerdeVecHashMap` for column data in the WAL following https://github.com/influxdata/influxdb/issues/25461
* refactor: roll back addition of DatabaseSchemaProvider trait
* refactor: make parquet metrics optional in telemetry for pro
* refactor: make ParquetFileId Hash
* refactor: test harness logging
* feat: Add TableId and ColumnId
* feat: swap over to DbId and TableId everywhere
This commit swaps us over to using the DbId and TableId types everywhere
for our internal systems. Anywhere that's external facing, such as names
for last cache tables or line protocol parsing, use names. In these cases
we have the `Catalog` which keeps a map of TableIds and DbIds in a
bidirectional mapping for easy lookup i.e. id <-> names. While in essence
the change itself isn't that complicated given the nature of how much we
depended on names for things, the changes end up being quite invasive and
extensive. Luckily it shouldn't be too hard to review. Note this does
not add the column ids which will be done in a follow up PR.
Closes#25375Closes#25403Closes#25404Closes#25405Closes#25412Closes#25413
* feat: Remove lock for FileId tests
Since we now are using cargo-nextest in CI we can remove
the locks used in the FileId tests to make sure that we
have no race conditions
* feat: Add u32 ID for Databases
This commit adds a new DbId for databases. It also updates paths to use
that id as part of the name. When starting up the WriteBuffer we apply
the DbId from the persisted snapshot much like we do for ParquetFileId's
This introduces the influxdb3_id crate to avoid circular deps with ids.
The ParquetFileId should also be moved into this crate, but it's
outside the scope of this change.
Closes#25301
Michael Gattozzi
Trevor Hilton