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Cleanup emitter some more #610

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Jan 4, 2025
Merged

Cleanup emitter some more #610

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234 changes: 234 additions & 0 deletions core/translate/aggregation.rs
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Original file line number Diff line number Diff line change
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use sqlite3_parser::ast;

use crate::{
function::AggFunc,
vdbe::{builder::ProgramBuilder, insn::Insn},
Result,
};

use super::{
emitter::{Resolver, TranslateCtx},
expr::translate_expr,
plan::{Aggregate, SelectPlan, TableReference},
result_row::emit_select_result,
};

/// Emits the bytecode for processing an aggregate without a GROUP BY clause.
/// This is called when the main query execution loop has finished processing,
/// and we can now materialize the aggregate results.
pub fn emit_ungrouped_aggregation<'a>(
program: &mut ProgramBuilder,
t_ctx: &mut TranslateCtx<'a>,
plan: &'a SelectPlan,
) -> Result<()> {
let agg_start_reg = t_ctx.reg_agg_start.unwrap();
for (i, agg) in plan.aggregates.iter().enumerate() {
let agg_result_reg = agg_start_reg + i;
program.emit_insn(Insn::AggFinal {
register: agg_result_reg,
func: agg.func.clone(),
});
}
// we now have the agg results in (agg_start_reg..agg_start_reg + aggregates.len() - 1)
// we need to call translate_expr on each result column, but replace the expr with a register copy in case any part of the
// result column expression matches a) a group by column or b) an aggregation result.
for (i, agg) in plan.aggregates.iter().enumerate() {
t_ctx
.resolver
.expr_to_reg_cache
.push((&agg.original_expr, agg_start_reg + i));
}

// This always emits a ResultRow because currently it can only be used for a single row result
// Limit is None because we early exit on limit 0 and the max rows here is 1
emit_select_result(program, t_ctx, plan, None)?;

Ok(())
}

/// Emits the bytecode for processing an aggregate step.
/// E.g. in `SELECT SUM(price) FROM t`, 'price' is evaluated for every row, and the result is added to the accumulator.
///
/// This is distinct from the final step, which is called after the main loop has finished processing
/// and the actual result value of the aggregation is materialized.
pub fn translate_aggregation_step(
program: &mut ProgramBuilder,
referenced_tables: &[TableReference],
agg: &Aggregate,
target_register: usize,
resolver: &Resolver,
) -> Result<usize> {
let dest = match agg.func {
AggFunc::Avg => {
if agg.args.len() != 1 {
crate::bail_parse_error!("avg bad number of arguments");
}
let expr = &agg.args[0];
let expr_reg = program.alloc_register();
let _ = translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: 0,
func: AggFunc::Avg,
});
target_register
}
AggFunc::Count => {
let expr_reg = if agg.args.is_empty() {
program.alloc_register()
} else {
let expr = &agg.args[0];
let expr_reg = program.alloc_register();
let _ = translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
expr_reg
};
program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: 0,
func: AggFunc::Count,
});
target_register
}
AggFunc::GroupConcat => {
if agg.args.len() != 1 && agg.args.len() != 2 {
crate::bail_parse_error!("group_concat bad number of arguments");
}

let expr_reg = program.alloc_register();
let delimiter_reg = program.alloc_register();

let expr = &agg.args[0];
let delimiter_expr: ast::Expr;

if agg.args.len() == 2 {
match &agg.args[1] {
ast::Expr::Column { .. } => {
delimiter_expr = agg.args[1].clone();
}
ast::Expr::Literal(ast::Literal::String(s)) => {
delimiter_expr = ast::Expr::Literal(ast::Literal::String(s.to_string()));
}
_ => crate::bail_parse_error!("Incorrect delimiter parameter"),
};
} else {
delimiter_expr = ast::Expr::Literal(ast::Literal::String(String::from("\",\"")));
}

translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
translate_expr(
program,
Some(referenced_tables),
&delimiter_expr,
delimiter_reg,
resolver,
)?;

program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: delimiter_reg,
func: AggFunc::GroupConcat,
});

target_register
}
AggFunc::Max => {
if agg.args.len() != 1 {
crate::bail_parse_error!("max bad number of arguments");
}
let expr = &agg.args[0];
let expr_reg = program.alloc_register();
let _ = translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: 0,
func: AggFunc::Max,
});
target_register
}
AggFunc::Min => {
if agg.args.len() != 1 {
crate::bail_parse_error!("min bad number of arguments");
}
let expr = &agg.args[0];
let expr_reg = program.alloc_register();
let _ = translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: 0,
func: AggFunc::Min,
});
target_register
}
AggFunc::StringAgg => {
if agg.args.len() != 2 {
crate::bail_parse_error!("string_agg bad number of arguments");
}

let expr_reg = program.alloc_register();
let delimiter_reg = program.alloc_register();

let expr = &agg.args[0];
let delimiter_expr = match &agg.args[1] {
ast::Expr::Column { .. } => agg.args[1].clone(),
ast::Expr::Literal(ast::Literal::String(s)) => {
ast::Expr::Literal(ast::Literal::String(s.to_string()))
}
_ => crate::bail_parse_error!("Incorrect delimiter parameter"),
};

translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
translate_expr(
program,
Some(referenced_tables),
&delimiter_expr,
delimiter_reg,
resolver,
)?;

program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: delimiter_reg,
func: AggFunc::StringAgg,
});

target_register
}
AggFunc::Sum => {
if agg.args.len() != 1 {
crate::bail_parse_error!("sum bad number of arguments");
}
let expr = &agg.args[0];
let expr_reg = program.alloc_register();
let _ = translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: 0,
func: AggFunc::Sum,
});
target_register
}
AggFunc::Total => {
if agg.args.len() != 1 {
crate::bail_parse_error!("total bad number of arguments");
}
let expr = &agg.args[0];
let expr_reg = program.alloc_register();
let _ = translate_expr(program, Some(referenced_tables), expr, expr_reg, resolver)?;
program.emit_insn(Insn::AggStep {
acc_reg: target_register,
col: expr_reg,
delimiter: 0,
func: AggFunc::Total,
});
target_register
}
};
Ok(dest)
}
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