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CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="PGSTATTUPLE"
>F.29. pgstattuple</A
></H1
><P
>  The <TT
CLASS="FILENAME"
>pgstattuple</TT
> module provides various functions to
  obtain tuple-level statistics.
 </P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN151240"
>F.29.1. Functions</A
></H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><CODE
CLASS="FUNCTION"
>pgstattuple(text) returns record</CODE
></DT
><DD
><P
>      <CODE
CLASS="FUNCTION"
>pgstattuple</CODE
> returns a relation's physical length,
      percentage of <SPAN
CLASS="QUOTE"
>"dead"</SPAN
> tuples, and other info. This may help users
      to determine whether vacuum is necessary or not.  The argument is the
      target relation's name (optionally schema-qualified).
      For example:
</P><PRE
CLASS="PROGRAMLISTING"
>test=&#62; SELECT * FROM pgstattuple('pg_catalog.pg_proc');
-[ RECORD 1 ]------+-------
table_len          | 458752
tuple_count        | 1470
tuple_len          | 438896
tuple_percent      | 95.67
dead_tuple_count   | 11
dead_tuple_len     | 3157
dead_tuple_percent | 0.69
free_space         | 8932
free_percent       | 1.95</PRE
><P>
     The output columns are described in <A
HREF="pgstattuple.html#PGSTATTUPLE-COLUMNS"
>Table F-23</A
>.
    </P
><DIV
CLASS="TABLE"
><A
NAME="PGSTATTUPLE-COLUMNS"
></A
><P
><B
>Table F-23. <CODE
CLASS="FUNCTION"
>pgstattuple</CODE
> Output Columns</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Column</TH
><TH
>Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>table_len</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Physical relation length in bytes</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>tuple_count</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Number of live tuples</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>tuple_len</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Total length of live tuples in bytes</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>tuple_percent</TT
></TD
><TD
><TT
CLASS="TYPE"
>float8</TT
></TD
><TD
>Percentage of live tuples</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>dead_tuple_count</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Number of dead tuples</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>dead_tuple_len</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Total length of dead tuples in bytes</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>dead_tuple_percent</TT
></TD
><TD
><TT
CLASS="TYPE"
>float8</TT
></TD
><TD
>Percentage of dead tuples</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>free_space</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Total free space in bytes</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>free_percent</TT
></TD
><TD
><TT
CLASS="TYPE"
>float8</TT
></TD
><TD
>Percentage of free space</TD
></TR
></TBODY
></TABLE
></DIV
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>        The <TT
CLASS="LITERAL"
>table_len</TT
> will always be greater than the sum
        of the <TT
CLASS="LITERAL"
>tuple_len</TT
>, <TT
CLASS="LITERAL"
>dead_tuple_len</TT
>
        and <TT
CLASS="LITERAL"
>free_space</TT
>. The difference is accounted for by
        fixed page overhead, the per-page table of pointers to tuples, and
        padding to ensure that tuples are correctly aligned. 
      </P
></BLOCKQUOTE
></DIV
><P
>     <CODE
CLASS="FUNCTION"
>pgstattuple</CODE
> acquires only a read lock on the
     relation. So the results do not reflect an instantaneous snapshot;
     concurrent updates will affect them.
    </P
><P
>     <CODE
CLASS="FUNCTION"
>pgstattuple</CODE
> judges a tuple is <SPAN
CLASS="QUOTE"
>"dead"</SPAN
> if
     <CODE
CLASS="FUNCTION"
>HeapTupleSatisfiesNow</CODE
> returns false.
    </P
></DD
><DT
><CODE
CLASS="FUNCTION"
>pgstattuple(oid) returns record</CODE
></DT
><DD
><P
>      This is the same as <CODE
CLASS="FUNCTION"
>pgstattuple(text)</CODE
>, except
      that the target relation is specified by OID.
     </P
></DD
><DT
><CODE
CLASS="FUNCTION"
>pgstatindex(text) returns record</CODE
></DT
><DD
><P
>      <CODE
CLASS="FUNCTION"
>pgstatindex</CODE
> returns a record showing information
      about a B-tree index.  For example:
</P><PRE
CLASS="PROGRAMLISTING"
>test=&#62; SELECT * FROM pgstatindex('pg_cast_oid_index');
-[ RECORD 1 ]------+------
version            | 2
tree_level         | 0
index_size         | 16384
root_block_no      | 1
internal_pages     | 0
leaf_pages         | 1
empty_pages        | 0
deleted_pages      | 0
avg_leaf_density   | 54.27
leaf_fragmentation | 0</PRE
><P>
     </P
><P
>     The output columns are:

    <DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN151342"
></A
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Column</TH
><TH
>Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>version</TT
></TD
><TD
><TT
CLASS="TYPE"
>integer</TT
></TD
><TD
>B-tree version number</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>tree_level</TT
></TD
><TD
><TT
CLASS="TYPE"
>integer</TT
></TD
><TD
>Tree level of the root page</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>index_size</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Total index size in bytes</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>root_block_no</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Location of root page (zero if none)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>internal_pages</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Number of <SPAN
CLASS="QUOTE"
>"internal"</SPAN
> (upper-level) pages</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>leaf_pages</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Number of leaf pages</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>empty_pages</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Number of empty pages</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>deleted_pages</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>Number of deleted pages</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>avg_leaf_density</TT
></TD
><TD
><TT
CLASS="TYPE"
>float8</TT
></TD
><TD
>Average density of leaf pages</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>leaf_fragmentation</TT
></TD
><TD
><TT
CLASS="TYPE"
>float8</TT
></TD
><TD
>Leaf page fragmentation</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
>
    </P
><P
>     The reported <TT
CLASS="LITERAL"
>index_size</TT
> will normally correspond to one more
     page than is accounted for by <TT
CLASS="LITERAL"
>internal_pages + leaf_pages +
     empty_pages + deleted_pages</TT
>, because it also includes the
     index's metapage.
    </P
><P
>     As with <CODE
CLASS="FUNCTION"
>pgstattuple</CODE
>, the results are accumulated
     page-by-page, and should not be expected to represent an
     instantaneous snapshot of the whole index.
    </P
></DD
><DT
><CODE
CLASS="FUNCTION"
>pg_relpages(text) returns bigint</CODE
></DT
><DD
><P
>      <CODE
CLASS="FUNCTION"
>pg_relpages</CODE
> returns the number of pages in the
      relation.
     </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN151422"
>F.29.2. Authors</A
></H2
><P
>   Tatsuo Ishii and Satoshi Nagayasu
  </P
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