godror is a package which is a database/sql/driver.Driver for connecting to Oracle DB, using Anthony Tuininga's excellent OCI wrapper, ODPI-C.
- Go 1.15
- C compiler with
CGO_ENABLED=1- so cross-compilation is hard
- Oracle Client libraries - see ODPI-C
Although Oracle Client libraries are NOT required for compiling, they are needed at run time. Download the free Basic or Basic Light package from https://www.oracle.com/database/technologies/instant-client/downloads.html.
With Go 1.9, driver-specific things are not needed, everything (I need) can be
achieved with the standard database/sql library. Even calling stored
procedures with OUT parameters, or sending/retrieving PL/SQL array types - just
give a godror.PlSQLArrays Option within the parameters of Exec (but not in sql.Named)!
For example, the array size of the returned PL/SQL arrays can be set with
godror.ArraySize(2000) (default value is 1024).
See Godror API Documentation and the Godror User Guide.
Run:
go get github.com/godror/godror@latestThen install Oracle Client libraries and you're ready to go!
godror is cgo package. If you want to build your app using godror, you need gcc (a C compiler).
Important: because this is a CGO enabled package,
you are required to set the environment variable CGO_ENABLED=1
and have a gcc compile present within your path.
See Godror Installation for more information.
To connect to Oracle Database use sql.Open("godror", dataSourceName),
where dataSourceName is a logfmt-encoded
parameter list. Specify at least "user", "password" and "connectString".
For example:
db, err := sql.Open("godror", `user="scott" password="tiger" connectString="dbhost:1521/orclpdb1"`)
The connectString can be ANYTHING that SQL*Plus or Oracle Call Interface
(OCI) accepts: a service name, an Easy Connect
string
like host:port/service_name, or a connect descriptor like (DESCRIPTION=...).
You can specify connection timeout seconds with "?connect_timeout=15" - Ping uses this timeout, NOT the Deadline in Context!
Note that connect_timeout requires at least 19c client.
For more connection options, see Godor Connection Handling.
To use the godror-specific functions, you'll need a *godror.conn.
That's what godror.DriverConn is for!
See z_qrcn_test.go for using that to reach
NewSubscription.
Use ExecContext and mark each OUT parameter with sql.Out.
As sql.DB will close the statement ASAP, for long-lived objects (LOB, REF CURSOR), you have to keep the Stmt alive: Prepare the statement, and Close only after finished with the Lob/Rows.
Use ExecContext and an interface{} or a database/sql/driver.Rows as the sql.Out destination,
then either use the driver.Rows interface,
or transform it into a regular *sql.Rows with godror.WrapRows,
or (since Go 1.12) just Scan into *sql.Rows.
As sql.DB will close the statemenet ASAP, you have to keep the Stmt alive: Prepare the statement, and Close only after finished with the Rows.
For examples, see Anthony Tuininga's presentation about Go (page 41)!
sql.NullString is not supported: Oracle DB does not differentiate between
an empty string ("") and a NULL, so an
sql.NullString{String:"", Valid:true} == sql.NullString{String:"", Valid:false}and this would be more confusing than not supporting sql.NullString at all.
Just use plain old string !
NUMBERs are transferred as string to Go under the hood.
This ensures that we don't lose any precision (Oracle's NUMBER has 38 decimal digits),
and sql.Scan will hide this and Scan into your int64, float64 or string, as you wish.
For PLS_INTEGER and BINARY_INTEGER (PL/SQL data types) you can use int32.
From 2.9.0, LOBs are returned as string/[]byte by default (before it needed the ClobAsString() option).
Now it's reversed, and the default is string, to get a Lob reader, give the LobAsReader() option.
Watch out, Oracle will error out if the CLOB is too large, and you have to use godror.Lob in such cases!
If you return Lob as a reader, watch out with sql.QueryRow, sql.QueryRowContext !
They close the statement right after you Scan from the returned *Row, the returned Lob will be invalid, producing
getSize: ORA-00000: DPI-1002: invalid dpiLob handle.
So, use a separate Stmt or sql.QueryContext.
For writing a LOB, the LOB locator returned from the database is valid only till the Stmt is valid!
So Prepare the statement for the retrieval, then Exec, and only Close the stmt iff you've finished with your LOB!
For example, see z_lob_test.go, TestLOBAppend.
As I couldn't make TIMESTAMP arrays work, all time.Time is bind as DATE, so fractional seconds
are lost.
A workaround is converting to string:
time.Now().Format("2-Jan-06 3:04:05.000000 PM")See #121 under the old project.
See the documentation - but for short, the database's OS' time zone is used,
as that's what SYSDATE/SYSTIMESTAMP uses. If you want something different (because you fill DATE columns differently),
then set the "location" in the connection string, or the Timezone in the ConnectionParams accord to your chosen timezone.
var rset1, rset2 driver.Rows
const query = `BEGIN Package.StoredProcA(123, :1, :2); END;`
stmt, err := db.PrepareContext(ctx, query)
if err != nil {
return fmt.Errorf("%s: %w", query, err)
}
defer stmt.Close()
if _, err := stmt.ExecContext(ctx, sql.Out{Dest: &rset1}, sql.Out{Dest: &rset2}); err != nil {
log.Printf("Error running %q: %+v", query, err)
return
}
defer rset1.Close()
defer rset2.Close()
cols1 := rset1.(driver.RowsColumnTypeScanType).Columns()
dests1 := make([]driver.Value, len(cols1))
for {
if err := rset1.Next(dests1); err != nil {
if err == io.EOF {
break
}
rset1.Close()
return err
}
fmt.Println(dests1)
}
cols2 := rset1.(driver.RowsColumnTypeScanType).Columns()
dests2 := make([]driver.Value, len(cols2))
for {
if err := rset2.Next(dests2); err != nil {
if err == io.EOF {
break
}
rset2.Close()
return err
}
fmt.Println(dests2)
}TL;DR; *always close sql.Rows ASAP!
Creating a watchdog goroutine, done channel for each call of rows.Next kills performance,
so we create only one watchdog goroutine, at the first rows.Next call.
It is defused after rows.Close (or the cursor is exhausted).
If it is not defused, it will Break the currently executing OCI call on the connection,
when the Context is canceled/timeouted. You should always call rows.Close ASAP, but if you
experience random Breaks, remember this warning!
Just as with other Go projects, you don't want to change the import paths, but you can hack on the library in place, just set up different remotes:
cd $GOPATH/src/github.com/godror/godror
git remote add upstream https://github.com/godror/godror.git
git fetch upstream
git checkout -b master upstream/master
git checkout -f master
git pull upstream master
git remote add fork [email protected]:mygithubacc/godror
git checkout -b newfeature upstream/masterChange, experiment as you wish. Then run
git commit -m 'my great changes' *.go
git push fork newfeatureand you're ready to send a GitHub Pull Request from the
github.com/mygithubacc/godror branch called newfeature.
Download a staticcheck release and add this to .git/hooks/pre-commit:
#!/bin/sh
set -e
output="$(gofmt -l "$@")"
if [ -n "$output" ]; then
echo >&2 "Go files must be formatted with gofmt. Please run:"
for f in $output; do
echo >&2 " gofmt -w $PWD/$f"
done
exit 1
fi
go run ./check
exec staticcheckAs ODPI stores the error buffer in a thread-local-storage, we must ensure that the error is retrieved on the same thread as the prvious function executed on.
This means we have to encapsulate each execute-then-retrieve-error sequence in
runtime.LockOSThread() and runtime.UnlockOSThread().
For details, see #120.
This is automatically detected by go run ./check which should be called in the pre-commit hook.
- oracall generates a server for calling stored procedures.
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