`INSERT OR IGNORE INTO t VALUES (...)` can trivially be rewritten to
`INSERT INTO t VALUES (..) ON CONFLICT DO NOTHING`
This PR does this rewriting, as well as finishes a large refactor on
INSERT translation in general.. I just need a break from the rest of
this feature tbh.. just was getting under my skin and I have been in
`translate` land for too long.
Closes#3742
This PR introduces a `Context` object that is stored in the `Completion`
that currently only stores a `Waker`. In the future, I want to add some
sort of abort signal so that we can abort tasks that share the same
Context. To pass the Waker, I introduced a `step_with_waker` function in
`Statement` that delegates to an internal `_step` function. `_step` is
the previous `step` but just with the `Option<&Waker>` argument.
I was going to try and have the BusyHandler by truly async as well, but
I decided to not do it here, because it will be slightly complicated to
achieve.
Closes#3535
Closes#3687 .
Previously, the `try_fold_expr_to_i64` function casted `NULL` as `0`
when evaluating expressions in `LIMIT` or `OFFSET` clauses. I removed
this function since evaluating the expression directly and relying on
the MustBeInt operation for casting seems to handle everything.
Closes#3695
I was sampling our performance and noticed that In the throughput test,
we were only setting the `PRAGMA synchronous = full` in `setup_database`
and not in the connection. Also we were not setting `PRAGMA fullfsync =
true`.
Now SQLite numbers and Turso numbers are much closer:
`Turso,1,1000,0,215095.94`
vs
`SQLite,1,1000,0,219748.39`
Specs: M2 Air 8gb
related: #3027Closes#3734
We merged two concurrent fixes to `nchange` handling last night and
AFAICT the fix in #3692 was incorrect because it doesn't count UPDATEs
in cases where the original row was DELETEd as part of the UPDATE
statement.
The correct fix was in 87434b8
EDIT: okay, it's not strictly _incorrect_ in #3692 I guess, I just think
it's more intuitive to increment the change for UPDATE in the `insert`
opcode because that's what performs the actual update.
Closes#3735
## Background
Simulator wants to create predicates that it knows will be Greater or
Less than some known value. It uses `LTValue` and `GTValue` for
generating these.
## Problem
Current implementation simply decrements or increments a random char by
1, and can thus generate strings with control characters like null
terminators that result in parse errors, as seen in e.g. this CI run htt
ps://github.com/tursodatabase/turso/actions/runs/18459131141/job/5258630
5749?pr=3702 of PR #3702
EDIT: I realized the _actual_ problem is in `GTValue` when it decides to
make the string longer, it uses a random char value from `0..255` which
can include null terminators etc. Fixed that too. I think in general
this PR's approach is a bit more predictable so let's keep it.
## Solution
Restrict string mutations to ascii string characters so that the
mutation always results in another ascii string character.
Closes#3708
We merged two concurrent fixes to `nchange` handling last night and
AFAICT the fix in #3692 was incorrect because it doesn't count UPDATEs
in cases where the original row was DELETEd as part of the UPDATE
statement.
The correct fix was in 87434b8
Closes#2600
## Problem
Every btree has a key it is sorted by - this is the integer `rowid` for
tables and an arbitrary-sized, potentially multi-column key for indexes.
Executing an UPDATE in a loop is not safe if the update modifies any
part of the key of the btree that is used for iterating the rows in said
loop. For example:
- Using the table itself to iterate rows is not safe if the UPDATE
modifies the rowid (or rowid alias) of a row, because since it modifies
the iteration order itself, it may cause rows to be skipped:
```sql
CREATE TABLE t(x INTEGER PRIMARY KEY, y);
INSERT <something>
UPDATE t SET y = RANDOM() where x > 100; // safe to iterate 't', 'y' is not being modified
UPDATE t SET x = RANDOM() where x > 100; // not safe to iterate 't', 'x' is being modified
```
- Using an index to iterate rows is not safe if the UPDATE modifies any
of the columns in the index key
```sql
CREATE TABLE t(x, y, z);
CREATE INDEX txy ON t (x,y);
INSERT <something>
UPDATE t SET z = RANDOM() where x = 100 and y > 0; // safe to iterate txy, neither x or y is being modified
UPDATE t SET x = RANDOM() where x = 100 and y > 0; // not safe to iterate txy, 'x' is being modified
UPDATE t SET y = RANDOM() where x = 100 and y > 0; // not safe to iterate txy, 'y' is being modified
```
## Current solution in tursodb
Our current `main` code recognizes this issue and adopts this pseudocode
algorithm from SQLite:
- open a table or index for reading the rows of the source table,
- for each row that matches the condition in the UPDATE statement, write
the row into a temporary table
- then use that temporary table for iteration in the UPDATE loop.
This guarantees that the iteration order will not be affected by the
UPDATEs because the ephemeral table is not under modification.
## Problem with current solution
Our `main` code specialcases the ephemeral table solution to rowids /
rowid aliases only. Using indexes for UPDATE iteration was disabled in
an earlier PR (#2599) due to the safety issue mentioned above, which
means that many UPDATE statements become full table scans:
```sql
turso> create table t(x PRIMARY KEY);
turso> insert into t select value from generate_series(1,10000);
turso> explain update t set x = x + 100000 where x > 50 and x < 60;
addr opcode p1 p2 p3 p4 p5 comment
---- ----------------- ---- ---- ---- ------------- -- -------
0 Init 0 28 0 0 Start at 28
1 OpenWrite 0 2 0 0 root=2; iDb=0
2 OpenWrite 1 3 0 0 root=3; iDb=0
-- scan entire 't' despite very narrow update range!
3 Rewind 0 27 0 0 Rewind table t
...
```
## Solution
We move the ephemeral table logic to _after_ the optimizer has selected
the best access path for the table, and then, if the UPDATE modifies the
key of the chosen access path (table or index; whichever was selected by
the optimizer), we change the plan to include the ephemeral table
prepopulation. Hence, the same query from above becomes:
```sql
turso> explain update t set x = x + 100000 where x > 50 and x < 60;
addr opcode p1 p2 p3 p4 p5 comment
---- ----------------- ---- ---- ---- ------------- -- -------
0 Init 0 35 0 0 Start at 35
1 OpenEphemeral 0 1 0 0 cursor=0 is_table=true
2 OpenRead 1 3 0 0 index=sqlite_autoindex_t_1, root=3, iDb=0
3 Integer 50 2 0 0 r[2]=50
-- index seek on PRIMARY KEY index
4 SeekGT 1 10 2 0 key=[2..2]
5 Integer 60 2 0 0 r[2]=60
6 IdxGE 1 10 2 0 key=[2..2]
7 IdxRowId 1 1 0 0 r[1]=cursor 1 for index sqlite_autoindex_t_1.rowid
8 Insert 0 3 1 ephemeral_scratch 2 intkey=r[1] data=r[3]
9 Next 1 6 0 0
10 OpenWrite 2 2 0 0 root=2; iDb=0
11 OpenWrite 3 3 0 0 root=3; iDb=0
-- only scan rows that were inserted to ephemeral index
12 Rewind 0 34 0 0 Rewind table ephemeral_scratch
13 RowId 0 5 0 0 r[5]=ephemeral_scratch.rowid
```
Note that an ephemeral index does not have to be used if the index is
not affected:
```sql
turso> create table t(x PRIMARY KEY, data);
turso> explain update t set data = 'some_data' where x > 50 and x < 60;
addr opcode p1 p2 p3 p4 p5 comment
---- ----------------- ---- ---- ---- ------------- -- -------
0 Init 0 15 0 0 Start at 15
1 OpenWrite 0 2 0 0 root=2; iDb=0
2 OpenWrite 1 3 0 0 root=3; iDb=0
3 Integer 50 1 0 0 r[1]=50
-- direct index seek
4 SeekGT 1 14 1 0 key=[1..1]
```
Reviewed-by: Preston Thorpe <preston@turso.tech>
Closes#3728
This PR contains NO semantic changes at all, this simply refactors
existing INSERT code to be easier to reason about.
Very sorry I know I've been working on `INSERT OR IGNORE|REPLACE|etc..`
for days now but the insert translation was literally unbearable and I
got it working but I barely could wrap my head around that whole
`translate_insert` function, so I spent a bunch of time refactoring the
whole INSERT handling out into different "Plans"... which turned into a
whole different clusterf***... So I just went back and made the existing
insert emission more modular and created some context that can make it
easier to reason about.
This should be able to just be merged quickly
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#3731
