I added the two opcodes as an initial step. They are pretty easy to
implement since we already have the counterparts i.e., IdxGE and IdxGT
Is there a design reason behind their omission @penberg @PThorpe92?
I noticed the same for SeekLE and SeekLT.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#1010
easy implementation, sqlite claims it is a noop now
"This pragma no longer functions. It has become a no-op. The capabilities
formerly provided by PRAGMA legacy_file_format are now available using
the SQLITE_DBCONFIG_LEGACY_FILE_FORMAT option to the sqlite3_db_config()
C-language interface."
After reading the fine print, SQLite documentation explains that `BEGIN
IMMEDIATE` and `BEGIN EXCLUSIVE` are the same thing in WAL mode:
https://www.sqlite.org/lang_transaction.html
As that's the only mode we support, let's just add code generation for
`BEGIN EXCLUSIVE`.
Fixes#1002Closes#1003
After reading the fine print, SQLite documentation explains that `BEGIN
IMMEDIATE` and `BEGIN EXCLUSIVE` are the same thing in WAL mode:
https://www.sqlite.org/lang_transaction.html
As that's the only mode we support, let's just add code generation for
`BEGIN EXCLUSIVE`.
Fixes#1002
Emit the following code sequence for `BEGIN IMMEDIATE`:
```
limbo> EXPLAIN BEGIN IMMEDIATE;
addr opcode p1 p2 p3 p4 p5 comment
---- ----------------- ---- ---- ---- ------------- -- -------
0 Init 0 4 0 0 Start at 4
1 Transaction 0 1 0 0
2 AutoCommit 0 0 0 0 auto_commit=false, rollback=false
3 Halt 0 0 0 0
4 Goto 0 1 0 0
```
Please note that SQLite emits *two* transaction instructions -- one for
main database and one for temporary tables. However, since we don't
support the latter, we only emit one transaction instruction.
Adds initial limited support for CTEs.
- No MATERIALIZED
- No RECURSIVE
- No named CTE columns
- Only SELECT statements supported inside CTE
Basically this kind of WITH clause can just be rewritten as a subquery,
so this PR adds some plumbing to rewrite them using the existing
subquery machinery.
It also introduces the concept of a `Scope` where a child query can
refer to its parent, useful for CTEs like:
```
do_execsql_test nested-subquery-cte {
with nested_sub as (
select concat(name, '!!!') as loud_hat
from products where name = 'hat'
),
sub as (
select upper(nested_sub.loud_hat) as loudest_hat from nested_sub
)
select sub.loudest_hat from sub;
} {HAT!!!}
```
I think we need to expand the use of `Scope` to all of our identifier
resolutions (currently we don't explicitly have logic for determining
what a given query can see), but I didn't want to bloat the PR too much.
Hence, this implementation is probably full of all sorts of bugs, but
I've added equivalent tests for ALL the existing subquery tests,
rewritten in CTE form.
Closes#920
Add basic printf function support in limbo
Closes#886
This PR implements json_pretty. At the moment, support for jsonb is
being added, so this function suffers from the same limitations as in
json(x). Also, I have not found a way to implement the same conversion
of Blob -> String that SQLite does. From my own experimentation, I
believe SQLite converts blobs to a lossy ascii representation, but I
would appreciate some help on this.
Closes#860
The main difference between = and != is how null values are handled.
SQLite passes a flag "NULLEQ" to Eq and Ne to disambiguate that.
In the presence of that flag, NULL = NULL.
Some prep work is done to make sure we can pass a flag instead of a
boolean to Eq and Ne. I looked into the bitflags crate but got a bit
scared with the list of dependencies.
Warning:
The following query produces a different result for Limbo:
```
select * from demo where value is null or id == 2;
```
I strongly suspect the issue is with the OR implementation, though. The
bytecode generated is quite different.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#847
This seems to really be just an alias for IS:
"The IS NOT DISTINCT FROM operator is an alternative spelling for the IS
operator. Likewise, the IS DISTINCT FROM operator means the same thing
as IS NOT. Standard SQL does not support the compact IS and IS NOT
notation. Those compact forms are an SQLite extension. You have to use
the prolix and much less readable IS NOT DISTINCT FROM and IS DISTINCT
FROM operators on other SQL database engines."
The main difference between = and != is how null values are handled.
SQLite passes a flag "NULLEQ" to Eq and Ne to disambiguate that.
In the presence of that flag, NULL = NULL.
Some prep work is done to make sure we can pass a flag instead of a
boolean to Eq and Ne. I looked into the bitflags crate but got a bit
scared with the list of dependencies.
Both () and = variants covered. It is important to make sure that
the transaction is a read transaction, so we cannot hide all that logic
inside update_pragma, and have to make our decision before that.
Take the logical OR of the values in register P1 and P2 and store the answer in register P3. If either P1 or P2 is nonzero (true) then the result is 1 (true) even if the other input is NULL. A NULL and false or two NULLs give a NULL output.
Take the logical AND of the values in registers P1 and P2 and write the result into register P3. If either P1 or P2 is 0 (false) then the result is 0 even if the other input is NULL. A NULL and true or two NULLs give a NULL output.
