go-oracledb is a package which is a database/sql/driver.Driver for connecting to Oracle DB, using Anthony Tuininga's excellent OCI wrapper, ODPI-C.
At least Go 1.11 is required!
Although an Oracle client is NOT required for compiling, it is at run time. One can download it from https://www.oracle.com/database/technologies/instant-client/downloads.html
In sql.Open("oracledb", connString), you can provide the classic "user/passw@service_name"
as connString, or an URL like "oracle://user:passw@service_name".
You can provide all possible options with ConnectionParams.
Watch out the ConnectionParams.String() does redact the password
(for security, to avoid logging it - see go-goracle/goracle#79).
So use ConnectionParams.StringWithPassword().
More advanced configurations can be set with a connection string such as:
user/pass@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=hostname)(PORT=port)))(CONNECT_DATA=(SERVICE_NAME=sn)))
A configuration like this is how you would add functionality such as load balancing across mutliple servers. The portion
described in parenthesis above can also be set in the SID field of ConnectionParams.
For other possible connection strings, see https://oracle.github.io/node-oracledb/doc/api.html#connectionstrings and https://www.oracle.com/pls/topic/lookup?ctx=dblatest&id=GUID-B0437826-43C1-49EC-A94D-B650B6A4A6EE .
TL;DR; the short form is username@[//]host[:port][/service_name][:server][/instance_name], the long form is
(DESCRIPTION= (ADDRESS=(PROTOCOL=tcp)(HOST=host)(PORT=port)) (CONNECT_DATA= (SERVICE_NAME=service_name) (SERVER=server) (INSTANCE_NAME=instance_name))).
To use heterogeneous pools, set heterogeneousPool=1 and provide the username/password through
oracledb.ContextWithUserPassw.
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
oracledb.PlSQLArrays Option within the parameters of Exec!
The array size of the returned PL/SQL arrays can be set with oracledb.ArraySize(2000)
- the default is 1024.
Connections are pooled by default (except AS SYSOPER or AS SYSDBA).
Correctness and simplicity is more important than speed, but the underlying ODPI-C library helps a lot with the lower levels, so the performance is not bad.
Queries are prefetched (256 rows by default, can be changed by adding a
oracledb.FetchRowCount(1000) argument to the call of Query),
but you can speed up INSERT/UPDATE/DELETE statements
by providing all the subsequent parameters at once, by putting each param's subsequent
elements in a separate slice:
Instead of
db.Exec("INSERT INTO table (a, b) VALUES (:1, :2)", 1, "a")
db.Exec("INSERT INTO table (a, b) VALUES (:1, :2)", 2, "b")
do
db.Exec("INSERT INTO table (a, b) VALUES (:1, :2)", []int{1, 2}, []string{"a", "b"})
Go-oracledb uses github.com/go-kit/kit/log's concept of a Log function.
Either set oracledb.Log to a logging function globally,
or (better) set the logger in the Context of ExecContext or QueryContext:
db.QueryContext(oracledb.ContextWithLog(ctx, logger.Log), qry)
To set ClientIdentifier, ClientInfo, Module, Action and DbOp on the session, to be seen in the Database by the Admin, set oracledb.TraceTag on the Context:
db.QueryContext(oracledb.ContextWithTraceTag(oracledb.TraceTag{
Module: "processing",
Action: "first",
}), qry)
To use the go-goracledb-specific functions, you'll need a *oracledb.conn.
That's what oracledb.DriverConn is for!
See z_qrcn_test.go for using that to reach
NewSubscription.
Use ExecContext and mark each OUT parameter with sql.Out.
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 oracledb.WrapRows,
or (since Go 1.12) just Scan into *sql.Rows.
For examples, see Anthony Tuininga's presentation about Go (page 39)!
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 oracledb.Number (which is a 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.
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.
Just
go get github.com/go-goracle/go-oracledb
Or if you prefer dep
dep ensure -add github.com/go-goracle/go-oracledb
and you're ready to go!
Note that Windows may need some newer gcc (mingw-w64 with gcc 7.2.0).
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 $GOPATH.src/github.com/go-goracle/go-oracledb
git remote add upstream https://github.com/go-goracle/go-oraceldb.git
git fetch upstream
git checkout -b master upstream/master
git checkout -f master
git pull upstream master
git remote add fork [email protected]:mygithubacc/go-oraceldb
git checkout -b newfeature upstream/master
Change, experiment as you wish, then
git commit -m 'my great changes' *.go
git push fork newfeature
and you're ready to send a GitHub Pull Request from github.com/mygithubacc/go-oraceldb, newfeature branch.
Add this to .git/hooks/pre-commit (after go get github.com/golangci/golangci-lint/cmd/golangci-lint)
#!/bin/sh
set -e
output="$(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
golangci-lint run
- oracall generates a server for calling stored procedures.