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vars.go
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vars.go
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// Copyright 2017 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
package sql
import (
"fmt"
"sort"
"strings"
"golang.org/x/net/context"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
"github.com/cockroachdb/cockroach/pkg/storage/engine/enginepb"
)
const (
// PgServerVersion is the latest version of postgres that we claim to support.
PgServerVersion = "9.5.0"
)
// sessionVar provides a unified interface for performing operations on
// variables such as the selected database, or desired syntax.
type sessionVar struct {
// Set performs mutations (usually on p.session) to effect the change
// desired by SET commands.
Set func(ctx context.Context, p *planner, values []parser.TypedExpr) error
// Get returns a string representation of a given variable to be used
// either by SHOW or in the pg_catalog table.
Get func(p *planner) string
// Reset performs mutations (usually on p.session) to effect the change
// desired by RESET commands.
Reset func(*planner) error
}
// nopVar is a placeholder for a number of settings sent by various client
// drivers which we do not support, but should simply ignore rather than
// throwing an error when trying to SET or SHOW them.
var nopVar = sessionVar{
Set: func(context.Context, *planner, []parser.TypedExpr) error { return nil },
Get: func(*planner) string { return "" },
Reset: func(*planner) error { return nil },
}
var varGen = map[string]sessionVar{
`database`: {
Set: func(ctx context.Context, p *planner, values []parser.TypedExpr) error {
dbName, err := p.getStringVal(`database`, values)
if err != nil {
return err
}
if len(dbName) != 0 {
// Verify database descriptor exists.
if _, err := MustGetDatabaseDesc(ctx, p.txn, p.getVirtualTabler(), dbName); err != nil {
return err
}
}
p.session.Database = dbName
p.evalCtx.Database = dbName
return nil
},
Get: func(p *planner) string { return p.session.Database },
Reset: func(p *planner) error {
p.session.Database = p.session.defaults.database
return nil
},
},
`default_transaction_isolation`: {
Set: func(_ context.Context, p *planner, values []parser.TypedExpr) error {
// It's unfortunate that clients want us to support both SET
// SESSION CHARACTERISTICS AS TRANSACTION ..., which takes the
// isolation level as keywords/identifiers (e.g. JDBC), and SET
// DEFAULT_TRANSACTION_ISOLATION TO '...', which takes an
// expression (e.g. psycopg2). But that's how it is. Just ensure
// this code keeps in sync with SetDefaultIsolation() in set.go.
s, err := p.getStringVal(`default_transaction_isolation`, values)
if err != nil {
return err
}
switch strings.ToUpper(s) {
case `READ UNCOMMITTED`, `READ COMMITTED`, `SNAPSHOT`:
p.session.DefaultIsolationLevel = enginepb.SNAPSHOT
case `REPEATABLE READ`, `SERIALIZABLE`:
p.session.DefaultIsolationLevel = enginepb.SERIALIZABLE
default:
return fmt.Errorf("set default_transaction_isolation: unknown isolation level: %q", s)
}
return nil
},
Get: func(p *planner) string { return p.session.DefaultIsolationLevel.String() },
Reset: func(p *planner) error {
p.session.DefaultIsolationLevel = enginepb.IsolationType(0)
return nil
},
},
`distsql`: {
Set: func(_ context.Context, p *planner, values []parser.TypedExpr) error {
s, err := p.getStringVal(`distsql`, values)
if err != nil {
return err
}
switch parser.Name(s).Normalize() {
case parser.ReNormalizeName("off"):
p.session.DistSQLMode = DistSQLOff
case parser.ReNormalizeName("on"):
p.session.DistSQLMode = DistSQLOn
case parser.ReNormalizeName("auto"):
p.session.DistSQLMode = DistSQLAuto
case parser.ReNormalizeName("always"):
p.session.DistSQLMode = DistSQLAlways
default:
return fmt.Errorf("set distsql: \"%s\" not supported", s)
}
return nil
},
Get: func(p *planner) string {
return p.session.DistSQLMode.String()
},
Reset: func(p *planner) error {
p.session.DistSQLMode = DistSQLExecModeFromInt(DistSQLClusterExecMode.Get())
if p.session.execCfg.TestingKnobs.OverrideDistSQLMode != nil {
p.session.DistSQLMode = DistSQLExecModeFromInt(p.session.execCfg.TestingKnobs.OverrideDistSQLMode.Get())
}
return nil
},
},
`search_path`: {
Set: func(_ context.Context, p *planner, values []parser.TypedExpr) error {
// https://www.postgresql.org/docs/9.6/static/runtime-config-client.html
newSearchPath := make(parser.SearchPath, len(values))
foundPgCatalog := false
for i, v := range values {
val, err := v.Eval(&p.evalCtx)
if err != nil {
return err
}
s, ok := parser.AsDString(val)
if !ok {
return fmt.Errorf("set search_path: requires string values: %s is %s not string",
v, val.ResolvedType())
}
if s == pgCatalogName {
foundPgCatalog = true
}
newSearchPath[i] = parser.Name(s).Normalize()
}
if !foundPgCatalog {
// "The system catalog schema, pg_catalog, is always searched,
// whether it is mentioned in the path or not. If it is
// mentioned in the path then it will be searched in the
// specified order. If pg_catalog is not in the path then it
// will be searched before searching any of the path items."
newSearchPath = append([]string{"pg_catalog"}, newSearchPath...)
}
p.session.SearchPath = newSearchPath
return nil
},
Get: func(p *planner) string { return strings.Join(p.session.SearchPath, ", ") },
Reset: func(p *planner) error {
p.session.SearchPath = sqlbase.DefaultSearchPath
return nil
},
},
`standard_conforming_strings`: {
Set: func(_ context.Context, p *planner, values []parser.TypedExpr) error {
// If true, escape backslash literals in strings. We do this by default,
// and we do not support the opposite behavior.
// See https://www.postgresql.org/docs/9.1/static/runtime-config-compatible.html#GUC-STANDARD-CONFORMING-STRINGS
s, err := p.getStringVal(`standard_conforming_strings`, values)
if err != nil {
return err
}
if parser.Name(s).Normalize() != parser.ReNormalizeName("on") {
return fmt.Errorf("set standard_conforming_strings: \"%s\" not supported", s)
}
return nil
},
Get: func(*planner) string { return "on" },
Reset: func(*planner) error { return nil },
},
`application_name`: {
Set: func(_ context.Context, p *planner, values []parser.TypedExpr) error {
// Set by clients to improve query logging.
// See https://www.postgresql.org/docs/9.6/static/runtime-config-logging.html#GUC-APPLICATION-NAME
s, err := p.getStringVal(`application_name`, values)
if err != nil {
return err
}
p.session.resetApplicationName(s)
return nil
},
Get: func(p *planner) string { return p.session.ApplicationName },
Reset: func(p *planner) error {
p.session.resetApplicationName(p.session.defaults.applicationName)
return nil
},
},
`time zone`: {
Get: func(p *planner) string {
// If the time zone is a "fixed offset" one, initialized from an offset
// and not a standard name, then we use a magic format in the Location's
// name. We attempt to parse that here and retrieve the original offset
// specified by the user.
_, origRepr, parsed := sqlbase.ParseFixedOffsetTimeZone(p.session.Location.String())
if parsed {
return origRepr
}
return p.session.Location.String()
},
},
`transaction isolation level`: {
Get: func(p *planner) string { return p.txn.Isolation().String() },
},
`transaction priority`: {
Get: func(p *planner) string { return p.txn.UserPriority().String() },
},
`transaction status`: {
Get: func(p *planner) string { return getTransactionState(&p.session.TxnState, p.autoCommit) },
},
`max_index_keys`: {
Get: func(*planner) string { return "32" },
},
`server_version`: {
Get: func(*planner) string { return PgServerVersion },
},
`session_user`: {
Get: func(p *planner) string { return p.session.User },
},
// See https://www.postgresql.org/docs/9.6/static/runtime-config-client.html
`extra_float_digits`: nopVar,
// Controls returned message verbosity. We don't support this.
// See https://www.postgresql.org/docs/9.6/static/runtime-config-compatible.html
`client_min_messages`: nopVar,
// See https://www.postgresql.org/docs/9.6/static/multibyte.html
`client_encoding`: {
Get: func(*planner) string {
return "UTF8"
},
Set: func(_ context.Context, p *planner, values []parser.TypedExpr) error {
s, err := p.getStringVal(`client_encoding`, values)
if err != nil {
return err
}
if strings.ToUpper(s) != "UTF8" {
return fmt.Errorf("non-UTF8 encoding %s not supported", s)
}
return nil
},
},
}
var varNames = func() []string {
res := make([]string, 0, len(varGen))
for vName := range varGen {
res = append(res, vName)
}
sort.Strings(res)
return res
}()