Makes it easier to test the feature:
```
$ cargo run -- --experimental-indexes
Limbo v0.0.22
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database
limbo> CREATE TABLE t(x);
limbo> CREATE INDEX t_idx ON t(x);
limbo> DROP INDEX t_idx;
```
Previously we implemented update as a simple `Delete` + `Insert`
procedure which seemed okay for the moment but it wasn't. `Delete` can
trigger balance and a post balance `seek` which will leave cursor
pointing to an invalid page which `Insert` will try to insert to.
We solve this by removing `Delete` from the execution plan and rely on
`Insert` to properly overwrite the cell where the rowid is the same as
the one we are inserting.
It is easy to chalk this fuzzer issue to erratic floating point
behaviour, but this is not the case here.
Currently, `exec_math_log` calculates log with arbitrary bases by using
the following formula: `log_a(b) ~= ln(b) / ln(a)`. This calculation is
an approximation with lots of its floating point precision lost to
dividing the results of natural logarithms.
By using the specialized versions of the log functions (`log2` &
`log10`), we can avoid this loss of precision.
SQLite also uses these specialized log functions when possible, so it
doesn't hurt to do the same thing when aiming for parity.
We were incorrectly setting `moved_before` as `false` after checking
for unique constraint violation, but the reality is that after the
uniqueness check, we are already correctly positioned -- if no match
was found, the cursor is positioned at either:
a) no row, or
b) at the first entry that is greater than the key we are inserting.
This means we don't have to move anymore and can just insert.
Closes#1528 .
- Modified `translate_select` so that the caller can define if the
statement is top-level statement or a subquery.
- Refactored `translate_insert` to offload the translation of multi-row
VALUES and SELECT statements to `translate_select`
- I did not try to change much of `populate_column_registers` as I did
not want to break `translate_virtual_table_insert`. Ideally, I would
want to unite this remaining logic folding `populate_column_registers`
into `populate_columns_multiple_rows` and the
`translate_virtual_table_insert` into `translate_insert`. But, I think
this may be best suited for a separate PR.
## TODO
- ~Tests~ - *Done*
- ~Need to emit a temp table when we are selecting and inserting into
the Same Table -
https://github.com/sqlite/sqlite/blob/master/src/insert.c#L1369~ -
*Done*
- Optimization when table have the exact same schema - open an Issue
about it
- Virtual Tables do not benefit yet from this feature - open an Issue
about it
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#1566
- Instead of using a confusing CheckpointStatus for many different things,
introduce the following statuses:
* PagerCacheflushStatus - cacheflush can result in either:
- the WAL being written to disk and fsynced
- but also a checkpoint to the main BD file, and fsyncing the main DB file
Reflect this in the type.
* WalFsyncStatus - previously CheckpointStatus was also used for this, even
though fsyncing the WAL doesn't checkpoint.
* CheckpointStatus/CheckpointResult is now used only for actual checkpointing.
- Rename HaltState to CommitState (program.halt_state -> program.commit_state)
- Make WAL a non-optional property in Pager
* This gets rid of a lot of if let Some(...) boilerplate
* For ephemeral indexes, provide a DummyWAL implementation that does nothing.
- Rename program.halt() to program.commit_txn()
- Add some documentation comments to structs and functions
Closes#1413 . Basically, SQLite emits a check in a transaction to see
if it is attempting to write. If the db is in read only mode, it throws
an error, else the statement is executed. Mirroring how Rusqlite does
it, I modified the `OpenFlags` to use bitflags to better configure how
we open our VFS. This modification, will enable us to run tests against
the same database in parallel.
Closes#1433
Previously `DELETE FROM ...` only emitted deletes for main table, but
this is incorrect as we want to remove entries from index tables as
well.
Closes#1383
