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conn.go
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conn.go
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package pgx
import (
"context"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"strconv"
"strings"
"time"
"github.com/jackc/pgx/v5/internal/sanitize"
"github.com/jackc/pgx/v5/internal/stmtcache"
"github.com/jackc/pgx/v5/pgconn"
"github.com/jackc/pgx/v5/pgtype"
)
// ConnConfig contains all the options used to establish a connection. It must be created by ParseConfig and
// then it can be modified. A manually initialized ConnConfig will cause ConnectConfig to panic.
type ConnConfig struct {
pgconn.Config
Tracer QueryTracer
// Original connection string that was parsed into config.
connString string
// StatementCacheCapacity is maximum size of the statement cache used when executing a query with "cache_statement"
// query exec mode.
StatementCacheCapacity int
// DescriptionCacheCapacity is the maximum size of the description cache used when executing a query with
// "cache_describe" query exec mode.
DescriptionCacheCapacity int
// DefaultQueryExecMode controls the default mode for executing queries. By default pgx uses the extended protocol
// and automatically prepares and caches prepared statements. However, this may be incompatible with proxies such as
// PGBouncer. In this case it may be preferable to use QueryExecModeExec or QueryExecModeSimpleProtocol. The same
// functionality can be controlled on a per query basis by passing a QueryExecMode as the first query argument.
DefaultQueryExecMode QueryExecMode
createdByParseConfig bool // Used to enforce created by ParseConfig rule.
}
// ParseConfigOptions contains options that control how a config is built such as getsslpassword.
type ParseConfigOptions struct {
pgconn.ParseConfigOptions
}
// Copy returns a deep copy of the config that is safe to use and modify.
// The only exception is the tls.Config:
// according to the tls.Config docs it must not be modified after creation.
func (cc *ConnConfig) Copy() *ConnConfig {
newConfig := new(ConnConfig)
*newConfig = *cc
newConfig.Config = *newConfig.Config.Copy()
return newConfig
}
// ConnString returns the connection string as parsed by pgx.ParseConfig into pgx.ConnConfig.
func (cc *ConnConfig) ConnString() string { return cc.connString }
// Conn is a PostgreSQL connection handle. It is not safe for concurrent usage. Use a connection pool to manage access
// to multiple database connections from multiple goroutines.
type Conn struct {
pgConn *pgconn.PgConn
config *ConnConfig // config used when establishing this connection
preparedStatements map[string]*pgconn.StatementDescription
statementCache stmtcache.Cache
descriptionCache stmtcache.Cache
queryTracer QueryTracer
batchTracer BatchTracer
copyFromTracer CopyFromTracer
prepareTracer PrepareTracer
notifications []*pgconn.Notification
doneChan chan struct{}
closedChan chan error
typeMap *pgtype.Map
wbuf []byte
eqb ExtendedQueryBuilder
}
// Identifier a PostgreSQL identifier or name. Identifiers can be composed of
// multiple parts such as ["schema", "table"] or ["table", "column"].
type Identifier []string
// Sanitize returns a sanitized string safe for SQL interpolation.
func (ident Identifier) Sanitize() string {
parts := make([]string, len(ident))
for i := range ident {
s := strings.ReplaceAll(ident[i], string([]byte{0}), "")
parts[i] = `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
}
return strings.Join(parts, ".")
}
var (
// ErrNoRows occurs when rows are expected but none are returned.
ErrNoRows = errors.New("no rows in result set")
// ErrTooManyRows occurs when more rows than expected are returned.
ErrTooManyRows = errors.New("too many rows in result set")
)
var (
errDisabledStatementCache = fmt.Errorf("cannot use QueryExecModeCacheStatement with disabled statement cache")
errDisabledDescriptionCache = fmt.Errorf("cannot use QueryExecModeCacheDescribe with disabled description cache")
)
// Connect establishes a connection with a PostgreSQL server with a connection string. See
// pgconn.Connect for details.
func Connect(ctx context.Context, connString string) (*Conn, error) {
connConfig, err := ParseConfig(connString)
if err != nil {
return nil, err
}
return connect(ctx, connConfig)
}
// ConnectWithOptions behaves exactly like Connect with the addition of options. At the present options is only used to
// provide a GetSSLPassword function.
func ConnectWithOptions(ctx context.Context, connString string, options ParseConfigOptions) (*Conn, error) {
connConfig, err := ParseConfigWithOptions(connString, options)
if err != nil {
return nil, err
}
return connect(ctx, connConfig)
}
// ConnectConfig establishes a connection with a PostgreSQL server with a configuration struct.
// connConfig must have been created by ParseConfig.
func ConnectConfig(ctx context.Context, connConfig *ConnConfig) (*Conn, error) {
// In general this improves safety. In particular avoid the config.Config.OnNotification mutation from affecting other
// connections with the same config. See https://github.com/jackc/pgx/issues/618.
connConfig = connConfig.Copy()
return connect(ctx, connConfig)
}
// ParseConfigWithOptions behaves exactly as ParseConfig does with the addition of options. At the present options is
// only used to provide a GetSSLPassword function.
func ParseConfigWithOptions(connString string, options ParseConfigOptions) (*ConnConfig, error) {
config, err := pgconn.ParseConfigWithOptions(connString, options.ParseConfigOptions)
if err != nil {
return nil, err
}
statementCacheCapacity := 512
if s, ok := config.RuntimeParams["statement_cache_capacity"]; ok {
delete(config.RuntimeParams, "statement_cache_capacity")
n, err := strconv.ParseInt(s, 10, 32)
if err != nil {
return nil, fmt.Errorf("cannot parse statement_cache_capacity: %w", err)
}
statementCacheCapacity = int(n)
}
descriptionCacheCapacity := 512
if s, ok := config.RuntimeParams["description_cache_capacity"]; ok {
delete(config.RuntimeParams, "description_cache_capacity")
n, err := strconv.ParseInt(s, 10, 32)
if err != nil {
return nil, fmt.Errorf("cannot parse description_cache_capacity: %w", err)
}
descriptionCacheCapacity = int(n)
}
defaultQueryExecMode := QueryExecModeCacheStatement
if s, ok := config.RuntimeParams["default_query_exec_mode"]; ok {
delete(config.RuntimeParams, "default_query_exec_mode")
switch s {
case "cache_statement":
defaultQueryExecMode = QueryExecModeCacheStatement
case "cache_describe":
defaultQueryExecMode = QueryExecModeCacheDescribe
case "describe_exec":
defaultQueryExecMode = QueryExecModeDescribeExec
case "exec":
defaultQueryExecMode = QueryExecModeExec
case "simple_protocol":
defaultQueryExecMode = QueryExecModeSimpleProtocol
default:
return nil, fmt.Errorf("invalid default_query_exec_mode: %s", s)
}
}
connConfig := &ConnConfig{
Config: *config,
createdByParseConfig: true,
StatementCacheCapacity: statementCacheCapacity,
DescriptionCacheCapacity: descriptionCacheCapacity,
DefaultQueryExecMode: defaultQueryExecMode,
connString: connString,
}
return connConfig, nil
}
// ParseConfig creates a ConnConfig from a connection string. ParseConfig handles all options that [pgconn.ParseConfig]
// does. In addition, it accepts the following options:
//
// - default_query_exec_mode.
// Possible values: "cache_statement", "cache_describe", "describe_exec", "exec", and "simple_protocol". See
// QueryExecMode constant documentation for the meaning of these values. Default: "cache_statement".
//
// - statement_cache_capacity.
// The maximum size of the statement cache used when executing a query with "cache_statement" query exec mode.
// Default: 512.
//
// - description_cache_capacity.
// The maximum size of the description cache used when executing a query with "cache_describe" query exec mode.
// Default: 512.
func ParseConfig(connString string) (*ConnConfig, error) {
return ParseConfigWithOptions(connString, ParseConfigOptions{})
}
// connect connects to a database. connect takes ownership of config. The caller must not use or access it again.
func connect(ctx context.Context, config *ConnConfig) (c *Conn, err error) {
if connectTracer, ok := config.Tracer.(ConnectTracer); ok {
ctx = connectTracer.TraceConnectStart(ctx, TraceConnectStartData{ConnConfig: config})
defer func() {
connectTracer.TraceConnectEnd(ctx, TraceConnectEndData{Conn: c, Err: err})
}()
}
// Default values are set in ParseConfig. Enforce initial creation by ParseConfig rather than setting defaults from
// zero values.
if !config.createdByParseConfig {
panic("config must be created by ParseConfig")
}
c = &Conn{
config: config,
typeMap: pgtype.NewMap(),
queryTracer: config.Tracer,
}
if t, ok := c.queryTracer.(BatchTracer); ok {
c.batchTracer = t
}
if t, ok := c.queryTracer.(CopyFromTracer); ok {
c.copyFromTracer = t
}
if t, ok := c.queryTracer.(PrepareTracer); ok {
c.prepareTracer = t
}
// Only install pgx notification system if no other callback handler is present.
if config.Config.OnNotification == nil {
config.Config.OnNotification = c.bufferNotifications
}
c.pgConn, err = pgconn.ConnectConfig(ctx, &config.Config)
if err != nil {
return nil, err
}
c.preparedStatements = make(map[string]*pgconn.StatementDescription)
c.doneChan = make(chan struct{})
c.closedChan = make(chan error)
c.wbuf = make([]byte, 0, 1024)
if c.config.StatementCacheCapacity > 0 {
c.statementCache = stmtcache.NewLRUCache(c.config.StatementCacheCapacity)
}
if c.config.DescriptionCacheCapacity > 0 {
c.descriptionCache = stmtcache.NewLRUCache(c.config.DescriptionCacheCapacity)
}
return c, nil
}
// Close closes a connection. It is safe to call Close on an already closed
// connection.
func (c *Conn) Close(ctx context.Context) error {
if c.IsClosed() {
return nil
}
err := c.pgConn.Close(ctx)
return err
}
// Prepare creates a prepared statement with name and sql. sql can contain placeholders for bound parameters. These
// placeholders are referenced positionally as $1, $2, etc. name can be used instead of sql with Query, QueryRow, and
// Exec to execute the statement. It can also be used with Batch.Queue.
//
// The underlying PostgreSQL identifier for the prepared statement will be name if name != sql or a digest of sql if
// name == sql.
//
// Prepare is idempotent; i.e. it is safe to call Prepare multiple times with the same name and sql arguments. This
// allows a code path to Prepare and Query/Exec without concern for if the statement has already been prepared.
func (c *Conn) Prepare(ctx context.Context, name, sql string) (sd *pgconn.StatementDescription, err error) {
if c.prepareTracer != nil {
ctx = c.prepareTracer.TracePrepareStart(ctx, c, TracePrepareStartData{Name: name, SQL: sql})
}
if name != "" {
var ok bool
if sd, ok = c.preparedStatements[name]; ok && sd.SQL == sql {
if c.prepareTracer != nil {
c.prepareTracer.TracePrepareEnd(ctx, c, TracePrepareEndData{AlreadyPrepared: true})
}
return sd, nil
}
}
if c.prepareTracer != nil {
defer func() {
c.prepareTracer.TracePrepareEnd(ctx, c, TracePrepareEndData{Err: err})
}()
}
var psName, psKey string
if name == sql {
digest := sha256.Sum256([]byte(sql))
psName = "stmt_" + hex.EncodeToString(digest[0:24])
psKey = sql
} else {
psName = name
psKey = name
}
sd, err = c.pgConn.Prepare(ctx, psName, sql, nil)
if err != nil {
return nil, err
}
if psKey != "" {
c.preparedStatements[psKey] = sd
}
return sd, nil
}
// Deallocate releases a prepared statement. Calling Deallocate on a non-existent prepared statement will succeed.
func (c *Conn) Deallocate(ctx context.Context, name string) error {
var psName string
sd := c.preparedStatements[name]
if sd != nil {
psName = sd.Name
} else {
psName = name
}
err := c.pgConn.Deallocate(ctx, psName)
if err != nil {
return err
}
if sd != nil {
delete(c.preparedStatements, name)
}
return nil
}
// DeallocateAll releases all previously prepared statements from the server and client, where it also resets the statement and description cache.
func (c *Conn) DeallocateAll(ctx context.Context) error {
c.preparedStatements = map[string]*pgconn.StatementDescription{}
if c.config.StatementCacheCapacity > 0 {
c.statementCache = stmtcache.NewLRUCache(c.config.StatementCacheCapacity)
}
if c.config.DescriptionCacheCapacity > 0 {
c.descriptionCache = stmtcache.NewLRUCache(c.config.DescriptionCacheCapacity)
}
_, err := c.pgConn.Exec(ctx, "deallocate all").ReadAll()
return err
}
func (c *Conn) bufferNotifications(_ *pgconn.PgConn, n *pgconn.Notification) {
c.notifications = append(c.notifications, n)
}
// WaitForNotification waits for a PostgreSQL notification. It wraps the underlying pgconn notification system in a
// slightly more convenient form.
func (c *Conn) WaitForNotification(ctx context.Context) (*pgconn.Notification, error) {
var n *pgconn.Notification
// Return already received notification immediately
if len(c.notifications) > 0 {
n = c.notifications[0]
c.notifications = c.notifications[1:]
return n, nil
}
err := c.pgConn.WaitForNotification(ctx)
if len(c.notifications) > 0 {
n = c.notifications[0]
c.notifications = c.notifications[1:]
}
return n, err
}
// IsClosed reports if the connection has been closed.
func (c *Conn) IsClosed() bool {
return c.pgConn.IsClosed()
}
func (c *Conn) die(err error) {
if c.IsClosed() {
return
}
ctx, cancel := context.WithCancel(context.Background())
cancel() // force immediate hard cancel
c.pgConn.Close(ctx)
}
func quoteIdentifier(s string) string {
return `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
}
// Ping delegates to the underlying *pgconn.PgConn.Ping.
func (c *Conn) Ping(ctx context.Context) error {
return c.pgConn.Ping(ctx)
}
// PgConn returns the underlying *pgconn.PgConn. This is an escape hatch method that allows lower level access to the
// PostgreSQL connection than pgx exposes.
//
// It is strongly recommended that the connection be idle (no in-progress queries) before the underlying *pgconn.PgConn
// is used and the connection must be returned to the same state before any *pgx.Conn methods are again used.
func (c *Conn) PgConn() *pgconn.PgConn { return c.pgConn }
// TypeMap returns the connection info used for this connection.
func (c *Conn) TypeMap() *pgtype.Map { return c.typeMap }
// Config returns a copy of config that was used to establish this connection.
func (c *Conn) Config() *ConnConfig { return c.config.Copy() }
// Exec executes sql. sql can be either a prepared statement name or an SQL string. arguments should be referenced
// positionally from the sql string as $1, $2, etc.
func (c *Conn) Exec(ctx context.Context, sql string, arguments ...any) (pgconn.CommandTag, error) {
if c.queryTracer != nil {
ctx = c.queryTracer.TraceQueryStart(ctx, c, TraceQueryStartData{SQL: sql, Args: arguments})
}
if err := c.deallocateInvalidatedCachedStatements(ctx); err != nil {
return pgconn.CommandTag{}, err
}
commandTag, err := c.exec(ctx, sql, arguments...)
if c.queryTracer != nil {
c.queryTracer.TraceQueryEnd(ctx, c, TraceQueryEndData{CommandTag: commandTag, Err: err})
}
return commandTag, err
}
func (c *Conn) exec(ctx context.Context, sql string, arguments ...any) (commandTag pgconn.CommandTag, err error) {
mode := c.config.DefaultQueryExecMode
var queryRewriter QueryRewriter
optionLoop:
for len(arguments) > 0 {
switch arg := arguments[0].(type) {
case QueryExecMode:
mode = arg
arguments = arguments[1:]
case QueryRewriter:
queryRewriter = arg
arguments = arguments[1:]
default:
break optionLoop
}
}
if queryRewriter != nil {
sql, arguments, err = queryRewriter.RewriteQuery(ctx, c, sql, arguments)
if err != nil {
return pgconn.CommandTag{}, fmt.Errorf("rewrite query failed: %w", err)
}
}
// Always use simple protocol when there are no arguments.
if len(arguments) == 0 {
mode = QueryExecModeSimpleProtocol
}
if sd, ok := c.preparedStatements[sql]; ok {
return c.execPrepared(ctx, sd, arguments)
}
switch mode {
case QueryExecModeCacheStatement:
if c.statementCache == nil {
return pgconn.CommandTag{}, errDisabledStatementCache
}
sd := c.statementCache.Get(sql)
if sd == nil {
sd, err = c.Prepare(ctx, stmtcache.StatementName(sql), sql)
if err != nil {
return pgconn.CommandTag{}, err
}
c.statementCache.Put(sd)
}
return c.execPrepared(ctx, sd, arguments)
case QueryExecModeCacheDescribe:
if c.descriptionCache == nil {
return pgconn.CommandTag{}, errDisabledDescriptionCache
}
sd := c.descriptionCache.Get(sql)
if sd == nil {
sd, err = c.Prepare(ctx, "", sql)
if err != nil {
return pgconn.CommandTag{}, err
}
c.descriptionCache.Put(sd)
}
return c.execParams(ctx, sd, arguments)
case QueryExecModeDescribeExec:
sd, err := c.Prepare(ctx, "", sql)
if err != nil {
return pgconn.CommandTag{}, err
}
return c.execPrepared(ctx, sd, arguments)
case QueryExecModeExec:
return c.execSQLParams(ctx, sql, arguments)
case QueryExecModeSimpleProtocol:
return c.execSimpleProtocol(ctx, sql, arguments)
default:
return pgconn.CommandTag{}, fmt.Errorf("unknown QueryExecMode: %v", mode)
}
}
func (c *Conn) execSimpleProtocol(ctx context.Context, sql string, arguments []any) (commandTag pgconn.CommandTag, err error) {
if len(arguments) > 0 {
sql, err = c.sanitizeForSimpleQuery(sql, arguments...)
if err != nil {
return pgconn.CommandTag{}, err
}
}
mrr := c.pgConn.Exec(ctx, sql)
for mrr.NextResult() {
commandTag, _ = mrr.ResultReader().Close()
}
err = mrr.Close()
return commandTag, err
}
func (c *Conn) execParams(ctx context.Context, sd *pgconn.StatementDescription, arguments []any) (pgconn.CommandTag, error) {
err := c.eqb.Build(c.typeMap, sd, arguments)
if err != nil {
return pgconn.CommandTag{}, err
}
result := c.pgConn.ExecParams(ctx, sd.SQL, c.eqb.ParamValues, sd.ParamOIDs, c.eqb.ParamFormats, c.eqb.ResultFormats).Read()
c.eqb.reset() // Allow c.eqb internal memory to be GC'ed as soon as possible.
return result.CommandTag, result.Err
}
func (c *Conn) execPrepared(ctx context.Context, sd *pgconn.StatementDescription, arguments []any) (pgconn.CommandTag, error) {
err := c.eqb.Build(c.typeMap, sd, arguments)
if err != nil {
return pgconn.CommandTag{}, err
}
result := c.pgConn.ExecPrepared(ctx, sd.Name, c.eqb.ParamValues, c.eqb.ParamFormats, c.eqb.ResultFormats).Read()
c.eqb.reset() // Allow c.eqb internal memory to be GC'ed as soon as possible.
return result.CommandTag, result.Err
}
type unknownArgumentTypeQueryExecModeExecError struct {
arg any
}
func (e *unknownArgumentTypeQueryExecModeExecError) Error() string {
return fmt.Sprintf("cannot use unregistered type %T as query argument in QueryExecModeExec", e.arg)
}
func (c *Conn) execSQLParams(ctx context.Context, sql string, args []any) (pgconn.CommandTag, error) {
err := c.eqb.Build(c.typeMap, nil, args)
if err != nil {
return pgconn.CommandTag{}, err
}
result := c.pgConn.ExecParams(ctx, sql, c.eqb.ParamValues, nil, c.eqb.ParamFormats, c.eqb.ResultFormats).Read()
c.eqb.reset() // Allow c.eqb internal memory to be GC'ed as soon as possible.
return result.CommandTag, result.Err
}
func (c *Conn) getRows(ctx context.Context, sql string, args []any) *baseRows {
r := &baseRows{}
r.ctx = ctx
r.queryTracer = c.queryTracer
r.typeMap = c.typeMap
r.startTime = time.Now()
r.sql = sql
r.args = args
r.conn = c
return r
}
type QueryExecMode int32
const (
_ QueryExecMode = iota
// Automatically prepare and cache statements. This uses the extended protocol. Queries are executed in a single round
// trip after the statement is cached. This is the default. If the database schema is modified or the search_path is
// changed after a statement is cached then the first execution of a previously cached query may fail. e.g. If the
// number of columns returned by a "SELECT *" changes or the type of a column is changed.
QueryExecModeCacheStatement
// Cache statement descriptions (i.e. argument and result types) and assume they do not change. This uses the extended
// protocol. Queries are executed in a single round trip after the description is cached. If the database schema is
// modified or the search_path is changed after a statement is cached then the first execution of a previously cached
// query may fail. e.g. If the number of columns returned by a "SELECT *" changes or the type of a column is changed.
QueryExecModeCacheDescribe
// Get the statement description on every execution. This uses the extended protocol. Queries require two round trips
// to execute. It does not use named prepared statements. But it does use the unnamed prepared statement to get the
// statement description on the first round trip and then uses it to execute the query on the second round trip. This
// may cause problems with connection poolers that switch the underlying connection between round trips. It is safe
// even when the database schema is modified concurrently.
QueryExecModeDescribeExec
// Assume the PostgreSQL query parameter types based on the Go type of the arguments. This uses the extended protocol
// with text formatted parameters and results. Queries are executed in a single round trip. Type mappings can be
// registered with pgtype.Map.RegisterDefaultPgType. Queries will be rejected that have arguments that are
// unregistered or ambiguous. e.g. A map[string]string may have the PostgreSQL type json or hstore. Modes that know
// the PostgreSQL type can use a map[string]string directly as an argument. This mode cannot.
QueryExecModeExec
// Use the simple protocol. Assume the PostgreSQL query parameter types based on the Go type of the arguments.
// Queries are executed in a single round trip. Type mappings can be registered with
// pgtype.Map.RegisterDefaultPgType. Queries will be rejected that have arguments that are unregistered or ambiguous.
// e.g. A map[string]string may have the PostgreSQL type json or hstore. Modes that know the PostgreSQL type can use
// a map[string]string directly as an argument. This mode cannot.
//
// QueryExecModeSimpleProtocol should have the user application visible behavior as QueryExecModeExec with minor
// exceptions such as behavior when multiple result returning queries are erroneously sent in a single string.
//
// QueryExecModeSimpleProtocol uses client side parameter interpolation. All values are quoted and escaped. Prefer
// QueryExecModeExec over QueryExecModeSimpleProtocol whenever possible. In general QueryExecModeSimpleProtocol
// should only be used if connecting to a proxy server, connection pool server, or non-PostgreSQL server that does
// not support the extended protocol.
QueryExecModeSimpleProtocol
)
func (m QueryExecMode) String() string {
switch m {
case QueryExecModeCacheStatement:
return "cache statement"
case QueryExecModeCacheDescribe:
return "cache describe"
case QueryExecModeDescribeExec:
return "describe exec"
case QueryExecModeExec:
return "exec"
case QueryExecModeSimpleProtocol:
return "simple protocol"
default:
return "invalid"
}
}
// QueryResultFormats controls the result format (text=0, binary=1) of a query by result column position.
type QueryResultFormats []int16
// QueryResultFormatsByOID controls the result format (text=0, binary=1) of a query by the result column OID.
type QueryResultFormatsByOID map[uint32]int16
// QueryRewriter rewrites a query when used as the first arguments to a query method.
type QueryRewriter interface {
RewriteQuery(ctx context.Context, conn *Conn, sql string, args []any) (newSQL string, newArgs []any, err error)
}
// Query sends a query to the server and returns a Rows to read the results. Only errors encountered sending the query
// and initializing Rows will be returned. Err() on the returned Rows must be checked after the Rows is closed to
// determine if the query executed successfully.
//
// The returned Rows must be closed before the connection can be used again. It is safe to attempt to read from the
// returned Rows even if an error is returned. The error will be the available in rows.Err() after rows are closed. It
// is allowed to ignore the error returned from Query and handle it in Rows.
//
// It is possible for a call of FieldDescriptions on the returned Rows to return nil even if the Query call did not
// return an error.
//
// It is possible for a query to return one or more rows before encountering an error. In most cases the rows should be
// collected before processing rather than processed while receiving each row. This avoids the possibility of the
// application processing rows from a query that the server rejected. The CollectRows function is useful here.
//
// An implementor of QueryRewriter may be passed as the first element of args. It can rewrite the sql and change or
// replace args. For example, NamedArgs is QueryRewriter that implements named arguments.
//
// For extra control over how the query is executed, the types QueryExecMode, QueryResultFormats, and
// QueryResultFormatsByOID may be used as the first args to control exactly how the query is executed. This is rarely
// needed. See the documentation for those types for details.
func (c *Conn) Query(ctx context.Context, sql string, args ...any) (Rows, error) {
if c.queryTracer != nil {
ctx = c.queryTracer.TraceQueryStart(ctx, c, TraceQueryStartData{SQL: sql, Args: args})
}
if err := c.deallocateInvalidatedCachedStatements(ctx); err != nil {
if c.queryTracer != nil {
c.queryTracer.TraceQueryEnd(ctx, c, TraceQueryEndData{Err: err})
}
return &baseRows{err: err, closed: true}, err
}
var resultFormats QueryResultFormats
var resultFormatsByOID QueryResultFormatsByOID
mode := c.config.DefaultQueryExecMode
var queryRewriter QueryRewriter
optionLoop:
for len(args) > 0 {
switch arg := args[0].(type) {
case QueryResultFormats:
resultFormats = arg
args = args[1:]
case QueryResultFormatsByOID:
resultFormatsByOID = arg
args = args[1:]
case QueryExecMode:
mode = arg
args = args[1:]
case QueryRewriter:
queryRewriter = arg
args = args[1:]
default:
break optionLoop
}
}
if queryRewriter != nil {
var err error
originalSQL := sql
originalArgs := args
sql, args, err = queryRewriter.RewriteQuery(ctx, c, sql, args)
if err != nil {
rows := c.getRows(ctx, originalSQL, originalArgs)
err = fmt.Errorf("rewrite query failed: %w", err)
rows.fatal(err)
return rows, err
}
}
// Bypass any statement caching.
if sql == "" {
mode = QueryExecModeSimpleProtocol
}
c.eqb.reset()
rows := c.getRows(ctx, sql, args)
var err error
sd, explicitPreparedStatement := c.preparedStatements[sql]
if sd != nil || mode == QueryExecModeCacheStatement || mode == QueryExecModeCacheDescribe || mode == QueryExecModeDescribeExec {
if sd == nil {
sd, err = c.getStatementDescription(ctx, mode, sql)
if err != nil {
rows.fatal(err)
return rows, err
}
}
if len(sd.ParamOIDs) != len(args) {
rows.fatal(fmt.Errorf("expected %d arguments, got %d", len(sd.ParamOIDs), len(args)))
return rows, rows.err
}
rows.sql = sd.SQL
err = c.eqb.Build(c.typeMap, sd, args)
if err != nil {
rows.fatal(err)
return rows, rows.err
}
if resultFormatsByOID != nil {
resultFormats = make([]int16, len(sd.Fields))
for i := range resultFormats {
resultFormats[i] = resultFormatsByOID[uint32(sd.Fields[i].DataTypeOID)]
}
}
if resultFormats == nil {
resultFormats = c.eqb.ResultFormats
}
if !explicitPreparedStatement && mode == QueryExecModeCacheDescribe {
rows.resultReader = c.pgConn.ExecParams(ctx, sql, c.eqb.ParamValues, sd.ParamOIDs, c.eqb.ParamFormats, resultFormats)
} else {
rows.resultReader = c.pgConn.ExecPrepared(ctx, sd.Name, c.eqb.ParamValues, c.eqb.ParamFormats, resultFormats)
}
} else if mode == QueryExecModeExec {
err := c.eqb.Build(c.typeMap, nil, args)
if err != nil {
rows.fatal(err)
return rows, rows.err
}
rows.resultReader = c.pgConn.ExecParams(ctx, sql, c.eqb.ParamValues, nil, c.eqb.ParamFormats, c.eqb.ResultFormats)
} else if mode == QueryExecModeSimpleProtocol {
sql, err = c.sanitizeForSimpleQuery(sql, args...)
if err != nil {
rows.fatal(err)
return rows, err
}
mrr := c.pgConn.Exec(ctx, sql)
if mrr.NextResult() {
rows.resultReader = mrr.ResultReader()
rows.multiResultReader = mrr
} else {
err = mrr.Close()
rows.fatal(err)
return rows, err
}
return rows, nil
} else {
err = fmt.Errorf("unknown QueryExecMode: %v", mode)
rows.fatal(err)
return rows, rows.err
}
c.eqb.reset() // Allow c.eqb internal memory to be GC'ed as soon as possible.
return rows, rows.err
}
// getStatementDescription returns the statement description of the sql query
// according to the given mode.
//
// If the mode is one that doesn't require to know the param and result OIDs
// then nil is returned without error.
func (c *Conn) getStatementDescription(
ctx context.Context,
mode QueryExecMode,
sql string,
) (sd *pgconn.StatementDescription, err error) {
switch mode {
case QueryExecModeCacheStatement:
if c.statementCache == nil {
return nil, errDisabledStatementCache
}
sd = c.statementCache.Get(sql)
if sd == nil {
sd, err = c.Prepare(ctx, stmtcache.StatementName(sql), sql)
if err != nil {
return nil, err
}
c.statementCache.Put(sd)
}
case QueryExecModeCacheDescribe:
if c.descriptionCache == nil {
return nil, errDisabledDescriptionCache
}
sd = c.descriptionCache.Get(sql)
if sd == nil {
sd, err = c.Prepare(ctx, "", sql)
if err != nil {
return nil, err
}
c.descriptionCache.Put(sd)
}
case QueryExecModeDescribeExec:
return c.Prepare(ctx, "", sql)
}
return sd, err
}
// QueryRow is a convenience wrapper over Query. Any error that occurs while
// querying is deferred until calling Scan on the returned Row. That Row will
// error with ErrNoRows if no rows are returned.
func (c *Conn) QueryRow(ctx context.Context, sql string, args ...any) Row {
rows, _ := c.Query(ctx, sql, args...)
return (*connRow)(rows.(*baseRows))
}
// SendBatch sends all queued queries to the server at once. All queries are run in an implicit transaction unless
// explicit transaction control statements are executed. The returned BatchResults must be closed before the connection
// is used again.
func (c *Conn) SendBatch(ctx context.Context, b *Batch) (br BatchResults) {
if c.batchTracer != nil {
ctx = c.batchTracer.TraceBatchStart(ctx, c, TraceBatchStartData{Batch: b})
defer func() {
err := br.(interface{ earlyError() error }).earlyError()
if err != nil {
c.batchTracer.TraceBatchEnd(ctx, c, TraceBatchEndData{Err: err})
}
}()
}
if err := c.deallocateInvalidatedCachedStatements(ctx); err != nil {
return &batchResults{ctx: ctx, conn: c, err: err}
}
for _, bi := range b.QueuedQueries {
var queryRewriter QueryRewriter
sql := bi.SQL
arguments := bi.Arguments
optionLoop:
for len(arguments) > 0 {
// Update Batch.Queue function comment when additional options are implemented
switch arg := arguments[0].(type) {
case QueryRewriter:
queryRewriter = arg
arguments = arguments[1:]
default:
break optionLoop
}
}
if queryRewriter != nil {
var err error
sql, arguments, err = queryRewriter.RewriteQuery(ctx, c, sql, arguments)
if err != nil {
return &batchResults{ctx: ctx, conn: c, err: fmt.Errorf("rewrite query failed: %w", err)}
}
}
bi.SQL = sql
bi.Arguments = arguments
}
// TODO: changing mode per batch? Update Batch.Queue function comment when implemented
mode := c.config.DefaultQueryExecMode
if mode == QueryExecModeSimpleProtocol {
return c.sendBatchQueryExecModeSimpleProtocol(ctx, b)
}
// All other modes use extended protocol and thus can use prepared statements.
for _, bi := range b.QueuedQueries {
if sd, ok := c.preparedStatements[bi.SQL]; ok {
bi.sd = sd
}
}
switch mode {
case QueryExecModeExec:
return c.sendBatchQueryExecModeExec(ctx, b)
case QueryExecModeCacheStatement:
return c.sendBatchQueryExecModeCacheStatement(ctx, b)
case QueryExecModeCacheDescribe:
return c.sendBatchQueryExecModeCacheDescribe(ctx, b)
case QueryExecModeDescribeExec:
return c.sendBatchQueryExecModeDescribeExec(ctx, b)
default:
panic("unknown QueryExecMode")
}
}
func (c *Conn) sendBatchQueryExecModeSimpleProtocol(ctx context.Context, b *Batch) *batchResults {
var sb strings.Builder
for i, bi := range b.QueuedQueries {
if i > 0 {
sb.WriteByte(';')
}
sql, err := c.sanitizeForSimpleQuery(bi.SQL, bi.Arguments...)
if err != nil {
return &batchResults{ctx: ctx, conn: c, err: err}
}
sb.WriteString(sql)
}
mrr := c.pgConn.Exec(ctx, sb.String())
return &batchResults{
ctx: ctx,
conn: c,
mrr: mrr,
b: b,
qqIdx: 0,
}
}
func (c *Conn) sendBatchQueryExecModeExec(ctx context.Context, b *Batch) *batchResults {
batch := &pgconn.Batch{}
for _, bi := range b.QueuedQueries {
sd := bi.sd
if sd != nil {
err := c.eqb.Build(c.typeMap, sd, bi.Arguments)
if err != nil {
return &batchResults{ctx: ctx, conn: c, err: err}
}
batch.ExecPrepared(sd.Name, c.eqb.ParamValues, c.eqb.ParamFormats, c.eqb.ResultFormats)
} else {
err := c.eqb.Build(c.typeMap, nil, bi.Arguments)
if err != nil {
return &batchResults{ctx: ctx, conn: c, err: err}
}
batch.ExecParams(bi.SQL, c.eqb.ParamValues, nil, c.eqb.ParamFormats, c.eqb.ResultFormats)