reldatabase | pg_database.oid | Database for the relation.

relblocknumber | | Offset of the page in the relation.

isdirty | | Is the page dirty?

There is one row for each buffer in the shared cache. Unused buffers are

shown with all fields null except bufferid.

regression=# \d pg_buffercache;

View "public.pg_buffercache"

Column | Type | Modifiers

----------------+---------+-----------

bufferid | integer |

relfilenode | oid |

reltablespace | oid |

reldatabase | oid |

relblocknumber | bigint |

isdirty | boolean |

Column | Type | Modifiers

----------------+----------+-----------

bufferid | integer |

relfilenode | oid |

reltablespace | oid |

reldatabase | oid |

relblocknumber | bigint |

isdirty | boolean |

usagecount | smallint |

View definition:

SELECT p.bufferid, p.relfilenode, p.reltablespace, p.reldatabase,

p.relblocknumber, p.isdirty

p.relblocknumber, p.isdirty, p.usagecount

FROM pg_buffercache_pages() p(bufferid integer, relfilenode oid,

reltablespace oid, reldatabase oid, relblocknumber bigint,

isdirty boolean);

isdirty boolean, usagecount smallint);

regression=# SELECT c.relname, count(*) AS buffers

FROM pg_class c INNER JOIN pg_buffercache b

CREATE VIEW pg_buffercache AS

SELECT P.* FROM pg_buffercache_pages() AS P

(bufferid integer, relfilenode oid, reltablespace oid, reldatabase oid,

relblocknumber int8, isdirty bool);

relblocknumber int8, isdirty bool, usagecount int2);

-- Don't want these to be available at public.

REVOKE ALL ON FUNCTION pg_buffercache_pages() FROM PUBLIC;

PG_MODULE_MAGIC;

BlockNumberblocknum;

boolisvalid;

boolisdirty;

uint16usagecount;

}BufferCachePagesRec;

INT8OID,-1,0);

TupleDescInitEntry(tupledesc, (AttrNumber)6,"isdirty",

BOOLOID,-1,0);

TupleDescInitEntry(tupledesc, (AttrNumber)7,"usage_count",

INT2OID,-1,0);

fctx->tupdesc=BlessTupleDesc(tupledesc);

fctx->record[i].reltablespace=bufHdr->tag.rnode.spcNode;

fctx->record[i].reldatabase=bufHdr->tag.rnode.dbNode;

fctx->record[i].blocknum=bufHdr->tag.blockNum;

fctx->record[i].usagecount=bufHdr->usage_count;

if (bufHdr->flags&BM_DIRTY)

fctx->record[i].isdirty= true;

nulls[3]= true;

nulls[4]= true;

nulls[5]= true;

nulls[6]= true;

}

{

nulls[4]= false;

values[5]=BoolGetDatum(fctx->record[i].isdirty);

nulls[5]= false;

values[6]=Int16GetDatum(fctx->record[i].usagecount);

nulls[6]= false;

}