Coalesce adjacent free blocks during `page_free_array()` in
`core/storage/btree`.
Instead of immediately passing free cells to `free_cell_range()`, buffer
up to 10 free cells and try to merge adjacent free blocks. Break on the
first merge to avoid time complexity, `free_cell_range()` coalesces
blocks afterwards anyways. This follows SQLite's [`pageFreeArray()`](htt
ps://github.com/sqlite/sqlite/blob/d7324103b196c572a98724a5658970b4000b8
c39/src/btree.c#L7729) implementation.
Removed this TODO:
```rust
fn page_free_array( . . )
.
.
// TODO: implement fancy smart free block coalescing procedure instead of dumb free to
// then defragment
```
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#1448
This PR adds `PRAGMA schema_version` to get the value of the schema-
version integer at offset 40 in the database header.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#1427
Since `page_size` in `DatabaseHeader` can be 1 representing 65526 bytes,
it can't be used it directly. Additionally, we should use `u32` instead
of `u16` or `usize` in other contexts.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#1411
DeleteState had a bit too many unnecessary states so I removed them.
Usually we care about having a different state when I/O is triggered
requiring a state to be stored for later.
Furthermore, there was a bug with op_idx_delete where if balance is
triggered, op_idx_delete wouldn't be re-entrant. So a state machine was
added to prevent that from happening.
```bash
jussi@Jussis-MacBook-Pro limbo % git co main && cargo build --bin limbo --release && hyperfine --shell=none --warmup 5 './target/release/limbo TPC-H.db "select l_orderkey, 3 as revenue, o_orderdate, o_shippriority from lineitem, orders, customer where c_mktsegment = '\''FURNITURE'\'' and c_custkey = o_custkey and l_orderkey = o_orderkey and o_orderdate < cast('\''1995-03-29'\'' as datetime) and l_shipdate > cast('\''1995-03-29'\'' as datetime);"'
...
Benchmark 1: ./target/release/limbo TPC-H.db "select l_orderkey, 3 as revenue, o_orderdate, o_shippriority from lineitem, orders, customer where c_mktsegment = 'FURNITURE' and c_custkey = o_custkey and l_orderkey = o_orderkey and o_orderdate < cast('1995-03-29' as datetime) and l_shipdate > cast('1995-03-29' as datetime);"
Time (mean ± σ): 2.104 s ± 0.006 s [User: 1.952 s, System: 0.151 s]
Range (min … max): 2.094 s … 2.115 s 10 runs
jussi@Jussis-MacBook-Pro limbo % git co move-to-micro-opt && cargo build --bin limbo --release && hyperfine --shell=none --warmup 5 './target/release/limbo TPC-H.db "select l_orderkey, 3 as revenue, o_orderdate, o_shippriority from lineitem, orders, customer where c_mktsegment = '\''FURNITURE'\'' and c_custkey = o_custkey and l_orderkey = o_orderkey and o_orderdate < cast('\''1995-03-29'\'' as datetime) and l_shipdate > cast('\''1995-03-29'\'' as datetime);"'
...
Benchmark 1: ./target/release/limbo TPC-H.db "select l_orderkey, 3 as revenue, o_orderdate, o_shippriority from lineitem, orders, customer where c_mktsegment = 'FURNITURE' and c_custkey = o_custkey and l_orderkey = o_orderkey and o_orderdate < cast('1995-03-29' as datetime) and l_shipdate > cast('1995-03-29' as datetime);"
Time (mean ± σ): 1.883 s ± 0.012 s [User: 1.733 s, System: 0.146 s]
Range (min … max): 1.866 s … 1.908 s 10 runs
```
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#1408
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
