79 lines
1.9 KiB
Go
79 lines
1.9 KiB
Go
package aggregation
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import (
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"github.com/juju/errors"
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"github.com/pingcap/tidb/sessionctx/stmtctx"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/util/codec"
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"github.com/pingcap/tidb/util/mvmap"
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)
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// distinctChecker stores existing keys and checks if given data is distinct.
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type distinctChecker struct {
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existingKeys *mvmap.MVMap
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buf []byte
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}
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// createDistinctChecker creates a new distinct checker.
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func createDistinctChecker() *distinctChecker {
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return &distinctChecker{
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existingKeys: mvmap.NewMVMap(),
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}
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}
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// Check checks if values is distinct.
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func (d *distinctChecker) Check(values []types.Datum) (bool, error) {
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d.buf = d.buf[:0]
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var err error
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d.buf, err = codec.EncodeValue(d.buf, values...)
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if err != nil {
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return false, errors.Trace(err)
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}
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v := d.existingKeys.Get(d.buf)
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if v != nil {
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return false, nil
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}
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d.existingKeys.Put(d.buf, []byte{})
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return true, nil
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}
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// calculateSum adds v to sum.
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func calculateSum(sc *stmtctx.StatementContext, sum, v types.Datum) (data types.Datum, err error) {
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// for avg and sum calculation
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// avg and sum use decimal for integer and decimal type, use float for others
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// see https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html
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switch v.Kind() {
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case types.KindNull:
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case types.KindInt64, types.KindUint64:
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var d *types.MyDecimal
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d, err = v.ToDecimal(sc)
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if err == nil {
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data = types.NewDecimalDatum(d)
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}
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case types.KindMysqlDecimal:
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data = types.CopyDatum(v)
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default:
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var f float64
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f, err = v.ToFloat64(sc)
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if err == nil {
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data = types.NewFloat64Datum(f)
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}
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}
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if err != nil {
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return data, errors.Trace(err)
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}
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if data.IsNull() {
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return sum, nil
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}
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switch sum.Kind() {
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case types.KindNull:
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return data, nil
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case types.KindFloat64, types.KindMysqlDecimal:
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return types.ComputePlus(sum, data)
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default:
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return data, errors.Errorf("invalid value %v for aggregate", sum.Kind())
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}
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}
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