Improve allocation usage from ImmutableRecords by reusing them.
ImmutableRecord is basically a contigous piece of memory that holds the
current record. If we move to some other record we usually deallocate
the previous one and allocate a new one -- obviously this is wasteful.
With this commit we will reuse the ImmutableRecord to allow payload to
be extended if needed or reused if we can, making it faster to iterate
records basically.
Closes#1206Closes#447Closes#1117
Issues:
1. Rust floating point math fucntions are non deterministic.
2. SQLite have complex floating point display rules.
I changed rust functions to libm for math ops and implemented Display
trait for OwnedValue:Float. A lot of float formatting SQLite probably
inherits from C have to be handcrafted.
Closes#1208
### The problem:
I often need to copy the output of an `Explain` statement to my
clipboard. Currently this is not possible because it currently will only
write to stdout.
All other limbo output, I am able to run `.output file` in the CLI, then
enter my query and in another tmux pane I simply `cat file | xclip -in
-selection clipboard`.
### The solution:
Expose a `statement.explain()` method that returns the query explanation
as a string. If the user uses something like `execute` instead of
prepare, it will default to `stdout` as expected, but this allows the
user to access the query plan on the prepared statement and do with it
what they please.
Closes#1166
OwnedValue has become a powerhouse of madness, mainly because I decided
to do it like that when I first introduced AggContext. I decided it was
enough and I introduced a `Register` struct that contains `OwnedValue`,
`Record` and `Aggregation`, this way we don't use `OwnedValue` for
everything make everyone's life harder.
This is the next step towards making ImmutableRecords the default
because I want to remove unnecessary allocations. Right now we clone
OwnedValues when we generate a record more than needed.
We currently have two value types, `Value` and `OwnedValue`. The
original thinking was that `Value` is external type and `OwnedValue` is
internal type. However, this just results in unnecessary transformation
between the types as data crosses the Limbo library boundary.
Let's just follow SQLite here and consolidate on a single value type
(where `sqlite3_value` is just an alias for the internal `Mem` type).
The way this will eventually work is that we can have bunch of
pre-allocated `OwnedValue` objects in `ProgramState` and basically
return a reference to them all the way to the application itself, which
extracts the actual value.
In the INSERT statement generated by dump function, if the type affinity
of the value is TEXT, replace each single quotation mark with two single
quotation marks, and wrap it with single quotation marks.
This is a basic support for the very useful .dump command.
It doesn't yet implement any of the dump options sqlite has,
and it doesn't add some of the logic for things like indexes,
since we don't have them.
Bug: Infinite loop when parsing unclosed string literal
To reproduce:
Run query: `SELECT max(';`
Current behavior:
- Query runner enters an infinite loop when encountering an unclosed
string literal and prints error
Fix:
- Throw error and stop query runner loop
Closes#988Closes#989
Move result row to `ProgramState` to mimic what SQLite does where `Vdbe`
struct has a `pResultRow` member. This makes it easier to deal with result
lifetime, but more importantly, eventually lazily parse values at the edges of
the API.
