Currently, each record header is decoded at least twice: once to
determine the record size within the read buffer (in order to construct
the `ImmutableRecord` instance), and again later when decoding the
record for comparison. This redundant decoding can have a noticeable
negative impact on performance when records are wide (eg. contain
multiple columns).
This update modifies the (de)serialization format for sorted chunk files
by prepending a record size varint to each record payload. As a result,
only a single varint needs to be decoded to determine the record size,
eliminating the need to decode the full record header during reads.
Closes#2176
Two of the opcodes we implement (OpenRead and Transaction) should have
an opcode specifying the database to use, but they don't.
Add it, and for now always use 0 (the main database).
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#2191
Two of the opcodes we implement (OpenRead and Transaction) should have
an opcode specifying the database to use, but they don't.
Add it, and for now always use 0 (the main database).
Fixes#1904
This PR changes the existing behaviour of Connection.execute to not
return 0, but the number of rows that have been changed by the operation
within. The changes are:
1. Adds a getter for n_change and the execute function now returns the
n_change value
2. Integration test to test the behaviour
Closes#1987
It is insane that SQLite even allows this.
They actually don't if "defensive mode" is enabled:
"It is always safe to read the schema_version, but changing the
schema_version can cause problems. For this reason, attempts to change
the value of schema_version are a silent no-op when defensive mode is
enabled for a database connection.
Warning: Misuse of this pragma can result in database corruption."
We also update the compat table, which was not updated to reflect
the read version of this pragma being implemented.
Closes#2165
The following sequence of events is possible:
- init_chunk_heap() called
- flush() gets called, and all chunks start writing to disk
- chunk A status is WriteComplete, so chunk.read() gets called on chunk
A
- chunk A sets its status to WaitingForRead
- some other chunk B is still in WaitingForWrite status after flush()
- for this reason, init_chunk_heap() returns IOResult::IO
- init_chunk_heap() is called again
- we panic because chunk A is in WaitingForRead status
So - we just allow WaitingForRead status in init_chunk_heap() instead.
This panic was caught thanks to Pedro's IO latency enhancement to the
sim!
Reviewed-by: Iaroslav Zeigerman (@izeigerman)
Closes#2166
I ended up hitting #1974 today and wanted to fix it. I worked with
Claude to generate a more comprehensive set of queries that could fail
aside from just the insert query described in the issue. He got most of
them right - lots of cases were indeed failing. The ones that were
gibberish, he told me I was absolutely right for pointing out they were
bad.
But alas. With the test cases generated, we can work on fixing it. The
place where the assertion was hit, all we need to do there is return
true (but we assert that this is indeed a string literal, it shouldn't
be anything else at this point).
There are then just a couple of places where we need to make sure we
handle double quotes correctly. We already tested for single quotes in a
couple of places, but never for double quotes.
There is one funny corner case where you can just select "col" from tbl,
and if there is no column "col" on the table, that is treated as a
string literal. We handle that too.
Fixes#1974Closes#2152
I ended up hitting #1974 today and wanted to fix it. I worked with
Claude to generate a more comprehensive set of queries that could fail
aside from just the insert query described in the issue. He got most of
them right - lots of cases were indeed failing. The ones that were
gibberish, he told me I was absolutely right for pointing out they were
bad.
But alas. With the test cases generated, we can work on fixing it. The
place where the assertion was hit, all we need to do there is return
true (but we assert that this is indeed a string literal, it shouldn't
be anything else at this point).
There are then just a couple of places where we need to make sure we
handle double quotes correctly. We already tested for single quotes in a
couple of places, but never for double quotes.
There is one funny corner case where you can just select "col" from tbl,
and if there is no column "col" on the table, that is treated as a
string literal. We handle that too.
Fixes#1974
The following sequence of events is possible:
- init_chunk_heap() called
- chunk A status is WriteComplete, so chunk.read() gets called on chunk A
- some other chunk B is in WaitingForWrite status after flush()
- init_chunk_heap() returns IOResult::IO
- init_chunk_heap() is called again
- we panic because chunk A is in WaitingForRead status
So - we just allow WaitingForRead status in init_chunk_heap() instead.
This panic was caught thanks to Pedro's IO latency enhancement to the sim!
Another fix extracted from running simulations on the #1988 branch.
When interior cell replacement happens as described in #2108,
we use the `cursor.prev()` method to locate the largest key in the
left subtree.
There was an error during backwards traversal in the `get_prev_record()`
method where the parent's cell index was set as `i32::MAX` but not properly
set to `cell_count + 1` (indicating that rightmost pointer has been visited).
The reason `i32::MAX` is used is that the cell count of the page is not
necessarily known at the time it is pushed to the stack.
This PR fixes the issue by setting the cell index of the parent properly
when visiting the rightmost child.
Fixes#2153.
Not so sure if SQLite doesn't rollback in more cases, we should
definitively check this out.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2154
pread and pwrite is usually less instructions then seek and read. Also
added possibility for io to retry if AGAIN error happens. And made write
to wait for Event::writable
Reviewed-by: Preston Thorpe (@PThorpe92)
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2010
