Re: Cache lookup failed for relation

<p dir="ltr">I'm confused by the error message. Is a cache miss an error condition?<p dir="ltr">Thanks<br /> Peter<div
class="gmail_quote">OnFeb 11, 2013 6:22 PM, "Tom Lane" <<a href="mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>>
wrote:<brtype="attribution" /><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex">David Clymer <<a
href="mailto:david.clymer@vistashare.com">david.clymer@vistashare.com</a>>writes:<br /> > I've been seeing the
followingerror in one database of ours:<br /> >   "cache lookup failed for relation 7640518"<br /><br /> Always the
sameOID, or does it change?<br /><br /> > The SQL that apparently triggers this is:<br /> >    drop table if
existsns_e5461ae570429d0b7863cce9ef4d4ead;<br /><br /> > Unfortunately, manual attempts to reproduce the issue have
failed.In<br /> > normal operation, this statement is run as one of several parallel queries,<br /> > and the
tablesare by nature, short lived. That said, they are not<br /> > temporary tables.<br /><br /> Hm ... what are the
parallelqueries exactly?  If you're doing something<br /> like dropping both ends of a foreign-key linkage in parallel,
I'dnot be<br /> very astonished by an error like this, especially not in 9.0.x.  It'd be<br /> basically a race
conditionbetween two sessions both locking the same<br /> table, but by the time the second one gets the lock, the
firstone has<br /> dropped the table.  (Robert Haas has done some great work towards<br /> eliminating this type of
racecondition lately, but it's sure not in<br /> 9.0.x.)<br /><br /> > One other item of note: db #2 has recently
hadan OID wrap-around, which<br /> > makes me suspect that plays some part in this behavior.<br /><br /> I don't
believethat theory at all.<br /><br />                         regards, tom lane<br /><br /><br /> --<br /> Sent via
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