lt_initdb — database cluster initialization tool, it creates a new LightDB database cluster
lt_initdb
[option
...] [ --pgdata
| -D
] directory
lt_initdb
database cluster initialization tool, it creates a new
LightDB database cluster. A database
cluster is a collection of databases that are managed by a single
server instance.
Creating a database cluster consists of creating the directories in
which the database data will live, generating the shared catalog
tables (tables that belong to the whole cluster rather than to any
particular database), and creating the template1
and postgres
databases. When you later create a
new database, everything in the template1
database is
copied. (Therefore, anything installed in template1
is automatically copied into each database created later.)
The postgres
database is a default database meant
for use by users, utilities and third party applications.
Although lt_initdb
will attempt to create the
specified data directory, it might not have permission if the parent
directory of the desired data directory is root-owned. To initialize
in such a setup, create an empty data directory as root, then use
chown
to assign ownership of that directory to the
database user account, then su
to become the
database user to run lt_initdb
.
lt_initdb
must be run as the user that will own the
server process, because the server needs to have access to the
files and directories that lt_initdb
creates.
Since the server cannot be run as root, you must not run
lt_initdb
as root either. (It will in fact refuse
to do so.)
For security reasons the new cluster created by lt_initdb
will only be accessible by the cluster owner by default. The
--allow-group-access
option allows any user in the same
group as the cluster owner to read files in the cluster. This is useful
for performing backups as a non-privileged user.
lt_initdb
initializes the database cluster's default
locale and character set encoding. The character set encoding,
collation order (LC_COLLATE
) and character set classes
(LC_CTYPE
, e.g., upper, lower, digit) can be set separately
for a database when it is created. lt_initdb
determines
those settings for the template1
database, which will
serve as the default for all other databases.
To alter the default collation order or character set classes, use the
--lc-collate
and --lc-ctype
options.
Collation orders other than C
or POSIX
also have
a performance penalty. For these reasons it is important to choose the
right locale when running lt_initdb
.
The remaining locale categories can be changed later when the server
is started. You can also use --locale
to set the
default for all locale categories, including collation order and
character set classes. All server locale values (lc_*
) can
be displayed via SHOW ALL
.
More details can be found in Section 21.1.
To alter the default encoding, use the --encoding
.
More details can be found in Section 21.3.
After lt_initdb
initializes the database cluster,
lt_initdb
record the directory where the database cluster stored
in $LTHOME/instance_list.conf
.
-A authmethod
--auth=authmethod
This option specifies the default authentication method for local
users used in lt_hba.conf
(host
and local
lines). lt_initdb
will
prepopulate lt_hba.conf
entries using the
specified authentication method for non-replication as well as
replication connections.
Do not use trust
unless you trust all local users on your
system. trust
is the default for ease of installation.
--auth-host=authmethod
This option specifies the authentication method for local users via
TCP/IP connections used in lt_hba.conf
(host
lines).
--auth-local=authmethod
This option specifies the authentication method for local users via
Unix-domain socket connections used in lt_hba.conf
(local
lines).
-p port
This option specifies the port for the database cluster. The default port is 5432.
-D directory
--pgdata=directory
This option specifies the directory where the database cluster
should be stored. This is the only information required by
lt_initdb
, but you can avoid writing it by
setting the LTDATA
environment variable, which
can be convenient since the database server
(lightdb
) can find the database
directory later by the same variable.
-E encoding
--encoding=encoding
Selects the encoding of the template database. This will also
be the default encoding of any database you create later,
unless you override it there. The default is derived from the locale, or
SQL_ASCII
if that does not work. The character sets supported by
the LightDB server are described
in Section 21.3.1.
-g
--allow-group-access
Allows users in the same group as the cluster owner to read all cluster
files created by lt_initdb
.
-u
--upgrade-mode
Create a database cluster without extensions, which is equivalent to using lt_initdb
directly.
-k
--data-checksums
Use checksums on data pages to help detect corruption by the
I/O system that would otherwise be silent. Enabling checksums
may incur a noticeable performance penalty. If set, checksums
are calculated for all objects, in all databases. All checksum
failures will be reported in the
pg_stat_database
view.
-K
--encryption-key-command
Used for Transparent Data Encryption. Before creating your database instance, you have to write some code to make sure that the key can be read by the database during startup and instance creation. The key is a 32-byte hex string.
Here is the most simplistic example possible:
cat /somewhere/provide_key.sh #!/bin/sh echo 882fb7c12e80280fd664c69d2d636913
All you need is a program that prints the key to stdout. Make sure that LightDB is able to execute this program:
chmod +x /somewhere/provide_key.sh
Note: You don't have to write a shell script – you can use any kind of executable such as a C, Go or Python.
Create the database instance:
lt_initdb -p 5432 -D ./data -K /somewhere/provide_key.sh
--locale=locale
Sets the default locale for the database cluster. If this
option is not specified, the locale is inherited from the
environment that lt_initdb
runs in. Locale
support is described in Section 21.1.
--lc-collate=locale
--lc-ctype=locale
--lc-messages=locale
--lc-monetary=locale
--lc-numeric=locale
--lc-time=locale
Like --locale
, but only sets the locale in
the specified category.
--no-locale
Equivalent to --locale=C
.
-N
--no-sync
By default, lt_initdb
will wait for all files to be
written safely to disk. This option causes lt_initdb
to return without waiting, which is faster, but means that a
subsequent operating system crash can leave the data directory
corrupt. Generally, this option is useful for testing, but should not
be used when creating a production installation.
--pwfile=filename
Makes lt_initdb
read the database superuser's password
from a file. The first line of the file is taken as the password.
-S
--sync-only
Safely write all database files to disk and exit. This does not perform any of the normal lt_initdb operations.
-T config
--text-search-config=config
Sets the default text search configuration. See default_text_search_config for further information.
-U username
--username=username
Selects the user name of the database superuser. This defaults
to the name of the effective user running
lt_initdb
. It is really not important what the
superuser's name is, but one might choose to keep the
customary name lightdb, even if the operating
system user's name is different.
-W
--pwprompt
Makes lt_initdb
prompt for a password
to give the database superuser. If you don't plan on using password
authentication, this is not important. Otherwise you won't be
able to use password authentication until you have a password
set up.
-X directory
--waldir=directory
This option specifies the directory where the write-ahead log should be stored.
--wal-segsize=size
Set the WAL segment size, in megabytes. This is the size of each individual file in the WAL log. The default size is 512 megabytes. The value must be a power of 2 between 1 and 1024 (megabytes). This option can only be set during initialization, and cannot be changed later.
It may be useful to adjust this size to control the granularity of WAL log shipping or archiving. Also, in databases with a high volume of WAL, the sheer number of WAL files per directory can become a performance and management problem. Increasing the WAL file size will reduce the number of WAL files.
--install-mode=mode
Database cluster installation mode, there are three installation modes.
single
: stand-alone version.
ha
: high availability version.
distributed
: distributed version.
The default installation mode is single
.
--compatible-type=type
Database cluster compatibility type, there are three compatibility types:
off
: not compatible with other database features.
mysql
: compatible with MySQL database features.
oracle
: compatible with Oracle database features.
The default compatibility type is off
.
Other, less commonly used, options are also available:
-d
--debug
Print debugging output from the bootstrap backend and a few other
messages of lesser interest for the general public.
The bootstrap backend is the program lt_initdb
uses to create the catalog tables. This option generates a tremendous
amount of extremely boring output.
-L directory
Specifies where lt_initdb
should find
its input files to initialize the database cluster. This is
normally not necessary. You will be told if you need to
specify their location explicitly.
-n
--no-clean
By default, when lt_initdb
determines that an error prevented it from completely creating the database
cluster, it removes any files it might have created before discovering
that it cannot finish the job. This option inhibits tidying-up and is
thus useful for debugging.
Other options:
-V
--version
Print the lt_initdb version and exit.
-?
--help
Show help about lt_initdb command line arguments, and exit.
LTDATA
Specifies the directory where the database cluster is to be
stored; can be overridden using the -D
option.
LT_COLOR
Specifies whether to use color in diagnostic messages. Possible values
are always
, auto
and
never
.
TZ
Specifies the default time zone of the created database cluster. The value should be a full time zone name (see Section 8.5.3).
This utility, like most other LightDB utilities, also uses the environment variables supported by libpq (see Section 31.14).
It is recommended to use lt_initdb
, otherwise some functions are unavailable.
If you are run initdb(not recommended)
directly, you can using like:
$LTHOME/scripts/5_lightdb_modify_para.sh $LTHOME $LTDATA OLTP/OLAP shared_buffers(MB) effective_cache_size(MB) $LTPORT $INSTALL_MODE $COMPATIBLE_TYPE $LTHOME/scripts/6_lightdb_start.sh $LTHOME $LTDATA (if not started) $LTHOME/scripts/8_lightdb_create_extension.sh $LTHOME $LTPORT $INSTALL_MODE