The MakeRecord instruction now accepts an optional affinity_str
parameter that applies column-specific type conversions before creating
records. When provided, the affinity string is applied
character-by-character to each register using the existing
apply_affinity_char() function, matching SQLite's behavior.
Fixes#2040Fixes#2041
On the syscall IO backend, on TPC-H query 12, the _dominating_ part
of the stack trace is trying to construct affinities from a character,
failing, allocating an error&string, and then immediately falling back to
Blob affinity and dropping the error&string.
Since I'm on vacation I won't spend cycles on figuring out why we are passing
an incorrect affinity in `flags.get_affinity()` and instead make this lazy PR
just to improve performance and stop doing silly things :]
This fairly long commit implements persistence for materialized view.
It is hard to split because of all the interdependencies between components,
so it is a one big thing. This commit message will at least try to go into
details about the basic architecture.
Materialized Views as tables
============================
Materialized views are now a normal table - whereas before they were a virtual
table. By making a materialized view a table, we can reuse all the
infrastructure for dealing with tables (cursors, etc).
One of the advantages of doing this is that we can create indexes on view
columns. Later, we should also be able to write those views to separate files
with ATTACH write.
Materialized Views as Zsets
===========================
The contents of the table are a ZSet: rowid, values, weight. Readers will
notice that because of this, the usage of the ZSet data structure dwindles
throughout the codebase. The main difference between our materialized ZSet and
the standard DBSP ZSet, is that obviously ours is backed by a BTree, not a Hash
(since SQLite tables are BTrees)
Aggregator State
================
In DBSP, the aggregator nodes also have state. To store that state, there is a
second table. The table holds all aggregators in the view, and there is one
table per view. That is __turso_internal_dbsp_state_{view_name}. The format of
that table is similar to a ZSet: rowid, serialized_values, weight. We serialize
the values because there will be many aggregators in the table. We can't rely
on a particular format for the values.
The Materialized View Cursor
============================
Reading from a Materialized View essentially means reading from the persisted
ZSet, and enhancing that with data that exists within the transaction.
Transaction data is ephemeral, so we do not materialize this anywhere: we have
a carefully crafted implementation of seek that takes care of merging weights
and stitching the two sets together.
`commit_txn` in MVCC was hacking its way through I/O until now. After
adding this and the test for concurrent writers we now see `busy` errors
returning as expected because there is no `commit` queueing happening
yet until next PR I open.
Closes#2895
@penberg this PR try to clean up `turso_parser`'s`fmt` code.
- `get_table_name` and `get_column_name` should return None when
table/column does not exist.
```rust
/// Context to be used in ToSqlString
pub trait ToSqlContext {
/// Given an id, get the table name
/// First Option indicates whether the table exists
///
/// Currently not considering aliases
fn get_table_name(&self, _id: TableInternalId) -> Option<&str> {
None
}
/// Given a table id and a column index, get the column name
/// First Option indicates whether the column exists
/// Second Option indicates whether the column has a name
fn get_column_name(&self, _table_id: TableInternalId, _col_idx: usize) -> Option<Option<&str>> {
None
}
// help function to handle missing table/column names
fn get_table_and_column_names(
&self,
table_id: TableInternalId,
col_idx: usize,
) -> (String, String) {
let table_name = self
.get_table_name(table_id)
.map(|s| s.to_owned())
.unwrap_or_else(|| format!("t{}", table_id.0));
let column_name = self
.get_column_name(table_id, col_idx)
.map(|opt| {
opt.map(|s| s.to_owned())
.unwrap_or_else(|| format!("c{col_idx}"))
})
.unwrap_or_else(|| format!("c{col_idx}"));
(table_name, column_name)
}
}
```
- remove `FmtTokenStream` because it is same as `WriteTokenStream `
- remove useless functions and simplify `ToTokens`
```rust
/// Generate token(s) from AST node
/// Also implements Display to make sure devs won't forget Display
pub trait ToTokens: Display {
/// Send token(s) to the specified stream with context
fn to_tokens<S: TokenStream + ?Sized, C: ToSqlContext>(
&self,
s: &mut S,
context: &C,
) -> Result<(), S::Error>;
// Return displayer representation with context
fn displayer<'a, 'b, C: ToSqlContext>(&'b self, ctx: &'a C) -> SqlDisplayer<'a, 'b, C, Self>
where
Self: Sized,
{
SqlDisplayer::new(ctx, self)
}
}
```
Closes#2748
Because we can abort a read_page completion, this means a page can be in
the cache but be unloaded and unlocked. However, if we do not evict that
page from the page cache, we will return an unloaded page later which
will trigger assertions later on. This is worsened by the fact that page
cache is not per `Statement`, so you can abort a completion in one
Statement, and trigger some error in the next one if we don't evict the
page in these circumstances.
Also, to propagate IO errors we need to return the Error from
IOCompletions on step.
Closes#2785
Using `usize` to compute file offsets caps us at ~16GB on 32-bit
systems. For example, with 4 KiB pages we can only address up to 1048576
pages; attempting the next page overflows a 32-bit usize and can wrap
the write offset, corrupting data. Switching our I/O APIs and offset
math to u64 avoids this overflow on 32-bit targets
Closes#2791
- check free list trunk and pages
- use shared hash map to check for duplicate references for pages
- properly check overflow pages
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#2816
My goal with this patch is to be able to implement the ProjectOperator
for DBSP circuits using VDBE for expression evaluation.
*not* doing so is dangerous for the following reason: we will end up
with different, subtle, and incompatible behavior between SQLite
expressions if they are used in views versus outside of views.
In fact, even in our prototype had them: our projection tests, which
used to pass, were actually wrong =) (sqlite would return something
different if those functions were executed outside the view context)
For optimization reasons, we single out trivial expressions: they don't
have go through VDBE. Trivial expressions are expressions that only
involve Columns, Literals, and simple operators on elements of the same
type. Even type coercion takes this out of the realm of trivial.
Everything that is not trivial, is then translated with translate_expr -
in the same way SQLite will, and then compiled with VDBE.
We can, over time, make this process much better. There are essentially
infinite opportunities for optimization here. But for now, the main
warts are:
* VDBE execution needs a connection
* There is no good way in VDBE to pass parameters to a program.
* It is almost trivial to pollute the original connection. For example,
we need to issue HALT for the program to stop, but seeing that halt
will usually cause the program to try and halt the original program.
Subprograms, like the ones we use in triggers are a possible solution,
but they are much more expensive to execute, especially given that our
execution would essentially have to have a program with no other role
than to wrap the subprogram.
Therefore, what I am doing is:
* There is an in-memory database inside the projection operator (an
obvious optimization is to share it with *all* projection operators).
* We obtain a connection to that database when the operator is created
* We use that connection to execute our VDBE, which offers a clean, safe
and isolated way to execute the expression.
* We feed the values to the program manually by editing the registers
directly.
If a connection does e.g. CREATE TABLE, it will start a "child statement"
to reparse the schema. That statement does not start its own transaction,
and so should not try to end the existing one either.
We had a logic bug where these steps would happen:
- `CREATE TABLE` executed successfully
- pread fault happens inside `ParseSchema` child stmt
- `handle_program_error()` is called
- `pager.end_tx()` returns immediately because `is_nested_stmt` is true
and we correctly no-op it.
- however, crucially: `handle_program_error()` then sets tx state to None
- parent statement now catches error from nested stmt and calls
`handle_program_error()`, which calls `pager.end_tx()` again, and since
txn state is None, when it calls `rollback()` we panic on the assertion
`"dirty pages should be empty for read txn"`
Solution:
Do not do _any_ error processing in `handle_program_error()` inside a nested
stmt. This means that the parent write txn is still active when it processes
the error from the child and we avoid this panic.
SQLite does not store the rowid alias column in the record at all
when it is a rowid alias, because the rowid is always stored anyway
in the record header.
We were storing `txid` in `ProgramState`, this meant it was impossible
to track interactive transactions. This was extracted to `Connection`
instead.
Moreover, transaction state for mvcc now is reset on commit.
Closes#2689
