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Merge pull request #116 from penberg/limit-zero-cleanup

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Simplify `LIMIT 0` handling in translate_select()
This commit is contained in:
Pekka Enberg
2024-07-11 09:58:35 +03:00
committed by GitHub
parent 46e34daccd d8078d5e19
commit db73092592
1 changed files with 53 additions and 46 deletions
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99
core/translate.rs
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@@ -177,59 +177,66 @@ fn translate_select(mut select: Select) -> Result<Program> {
None
}
});
let limit_insn = match parsed_limit {
let limit_goto = match parsed_limit {
Some(0) => Some(program.emit_placeholder()),
_ => {
if !select.src_tables.is_empty() {
translate_tables_begin(&mut program, &mut select);
_ => None,
};
let limit_insn = if !select.src_tables.is_empty() {
translate_tables_begin(&mut program, &mut select);
let (register_start, register_end) =
translate_columns(&mut program, &select)?;
let (register_start, register_end) =
translate_columns(&mut program, &select)?;
let mut limit_insn: Option<usize> = None;
if !select.exist_aggregation {
program.emit_insn(Insn::ResultRow {
start_reg: register_start,
count: register_end - register_start,
});
limit_insn = limit_reg.map(|_| program.emit_placeholder());
}
translate_tables_end(&mut program, &select);
if select.exist_aggregation {
let mut target = register_start;
for info in &select.column_info {
if let Some(func) = &info.func {
program.emit_insn(Insn::AggFinal {
register: target,
func: func.clone(),
});
}
target += info.columns_to_allocate;
}
// only one result row
program.emit_insn(Insn::ResultRow {
start_reg: register_start,
count: register_end - register_start,
});
limit_insn = limit_reg.map(|_| program.emit_placeholder());
}
limit_insn
} else{
assert!(!select.exist_aggregation);
let (register_start, register_end) =
translate_columns(&mut program, &select)?;
program.emit_insn(Insn::ResultRow {
start_reg: register_start,
count: register_end - register_start,
});
limit_reg.map(|_| program.emit_placeholder())
}
let mut limit_insn: Option<usize> = None;
if !select.exist_aggregation {
program.emit_insn(Insn::ResultRow {
start_reg: register_start,
count: register_end - register_start,
});
limit_insn = limit_reg.map(|_| program.emit_placeholder());
}
translate_tables_end(&mut program, &select);
if select.exist_aggregation {
let mut target = register_start;
for info in &select.column_info {
if let Some(func) = &info.func {
program.emit_insn(Insn::AggFinal {
register: target,
func: func.clone(),
});
}
target += info.columns_to_allocate;
}
// only one result row
program.emit_insn(Insn::ResultRow {
start_reg: register_start,
count: register_end - register_start,
});
limit_insn = limit_reg.map(|_| program.emit_placeholder());
}
limit_insn
} else{
assert!(!select.exist_aggregation);
let (register_start, register_end) =
translate_columns(&mut program, &select)?;
program.emit_insn(Insn::ResultRow {
start_reg: register_start,
count: register_end - register_start,
});
limit_reg.map(|_| program.emit_placeholder())
};
program.emit_insn(Insn::Halt);
let halt_offset = program.offset() - 1;
if let Some(limit_goto) = limit_goto {
program.fixup_insn(
limit_goto,
Insn::Goto {
target_pc: halt_offset,
},
);
}
if let Some(limit_insn) = limit_insn {
let insn = match parsed_limit {
Some(0) => Insn::Goto {