diff options
Diffstat (limited to 'doc/src/sgml/lobj.sgml')
| -rw-r--r-- | doc/src/sgml/lobj.sgml | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/doc/src/sgml/lobj.sgml b/doc/src/sgml/lobj.sgml index 291409fde0b..66467e00f37 100644 --- a/doc/src/sgml/lobj.sgml +++ b/doc/src/sgml/lobj.sgml @@ -41,7 +41,7 @@ larger than a single database page into a secondary storage area per table. This makes the large object facility partially obsolete. One remaining advantage of the large object facility is that it allows values - up to 2 GB in size, whereas <acronym>TOAST</acronym>ed fields can be at + up to 4 TB in size, whereas <acronym>TOAST</acronym>ed fields can be at most 1 GB. Also, large objects can be randomly modified using a read/write API that is more efficient than performing such operations using <acronym>TOAST</acronym>. @@ -237,7 +237,9 @@ int lo_open(PGconn *conn, Oid lobjId, int mode); <function>lo_open</function> returns a (non-negative) large object descriptor for later use in <function>lo_read</function>, <function>lo_write</function>, <function>lo_lseek</function>, - <function>lo_tell</function>, and <function>lo_close</function>. + <function>lo_lseek64</function>, <function>lo_tell</function>, + <function>lo_tell64</function>, <function>lo_truncate</function>, + <function>lo_truncate64</function>, and <function>lo_close</function>. The descriptor is only valid for the duration of the current transaction. On failure, -1 is returned. @@ -312,6 +314,7 @@ int lo_read(PGconn *conn, int fd, char *buf, size_t len); large object descriptor, call <synopsis> int lo_lseek(PGconn *conn, int fd, int offset, int whence); +pg_int64 lo_lseek64(PGconn *conn, int fd, pg_int64 offset, int whence); </synopsis> <indexterm><primary>lo_lseek</></> This function moves the current location pointer for the large object descriptor identified by @@ -321,7 +324,16 @@ int lo_lseek(PGconn *conn, int fd, int offset, int whence); <symbol>SEEK_CUR</> (seek from current position), and <symbol>SEEK_END</> (seek from object end). The return value is the new location pointer, or -1 on error. + <indexterm><primary>lo_lseek64</></> <function>lo_lseek64</function> + is a function for large objects larger than 2GB. <symbol>pg_int64</> + is defined as 8-byte integer type. </para> +<para> + <function>lo_lseek64</> is new as of <productname>PostgreSQL</productname> + 9.3; if this function is run against an older server version, it will + fail and return a negative value. +</para> + </sect2> <sect2 id="lo-tell"> @@ -332,9 +344,17 @@ int lo_lseek(PGconn *conn, int fd, int offset, int whence); call <synopsis> int lo_tell(PGconn *conn, int fd); +pg_int64 lo_tell64(PGconn *conn, int fd); </synopsis> <indexterm><primary>lo_tell</></> If there is an error, the return value is negative. + <indexterm><primary>lo_tell64</></> <function>lo_tell64</function> is + a function for large objects larger than 2GB. +</para> +<para> + <function>lo_tell64</> is new as of <productname>PostgreSQL</productname> + 9.3; if this function is run against an older server version, it will + fail and return a negative value. </para> </sect2> @@ -345,6 +365,7 @@ int lo_tell(PGconn *conn, int fd); To truncate a large object to a given length, call <synopsis> int lo_truncate(PGcon *conn, int fd, size_t len); +int lo_truncate64(PGcon *conn, int fd, pg_int64 len); </synopsis> <indexterm><primary>lo_truncate</></> truncates the large object descriptor <parameter>fd</> to length <parameter>len</>. The @@ -352,6 +373,8 @@ int lo_truncate(PGcon *conn, int fd, size_t len); previous <function>lo_open</function>. If <parameter>len</> is greater than the current large object length, the large object is extended with null bytes ('\0'). + <indexterm><primary>lo_truncate64</></> <function>lo_truncate64</function> + is a function for large objects larger than 2GB. </para> <para> @@ -359,7 +382,7 @@ int lo_truncate(PGcon *conn, int fd, size_t len); </para> <para> - On success <function>lo_truncate</function> returns + On success <function>lo_truncate</function> and <function>lo_truncate64</function> returns zero. On error, the return value is negative. </para> @@ -368,6 +391,11 @@ int lo_truncate(PGcon *conn, int fd, size_t len); 8.3; if this function is run against an older server version, it will fail and return a negative value. </para> +<para> + <function>lo_truncate64</> is new as of <productname>PostgreSQL</productname> + 9.3; if this function is run against an older server version, it will + fail and return a negative value. +</para> </sect2> <sect2 id="lo-close"> |