Re: unexpected result for wastedbytes query after vacuum full

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On Tue, Dec 10, 2019 at 11:43 AM Guillaume Lelarge <[email protected]>
wrote:

This query uses the column statistics to estimate bloat. AFAIK, json
> columns don't have statistics, so the estimation can't be relied on (for
> this specific table at least).
>

This was true prior to 9.5 (for xml at least, I don't know about json), but
should not be true from that release onward.  But still the difference
between 74440704 and 74506240, this does seem to me to be straining at a
gnat to swallow a camel.

Cheers,

Jeff

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<div dir=3D"ltr"><div dir=3D"ltr">On Tue, Dec 10, 2019 at 11:43 AM Guillaum=
e Lelarge &lt;<a href=3D"mailto:[email protected]">[email protected]=
nfo</a>&gt; wrote:</div><div dir=3D"ltr"><br></div><div class=3D"gmail_quot=
e"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><div =
class=3D"gmail_quote"><div>This query uses the column statistics to estimat=
e bloat. AFAIK, json columns don&#39;t have statistics, so the estimation c=
an&#39;t be relied on (for this specific table at least).</div></div></div>=
</blockquote><div><br></div><div>This was true prior to 9.5 (for xml at lea=
st, I don&#39;t know about json), but should not be true from that release =
onward.=C2=A0 But still=C2=A0the difference between=C2=A0<span style=3D"col=
or:rgb(80,0,80)">74440704 and=C2=A0</span><span style=3D"color:rgb(0,0,0)">=
74506240</span>, this does seem to me to be straining at a gnat to swallow =
a camel.</div><div><br></div><div>Cheers,</div><div><br></div><div>Jeff</di=
v></div></div>

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