support extending indexscan,heapscan and customizing plan

<div class="Section1" style="layout-grid:15.6pt"><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US"
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9.0pt;font-family:Arial">Hi,</span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US"
style="font-size:
9.0pt;font-family:Arial">   we currently want to employ PG and Gin Index for light-weight full text search engine.
however,</span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">we encounter a problem that Gin Index is not quick enough for relevence, because it
must</span></font><pclass="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">scan all heaptuples which statisfy the condition, then invoke ts_rank to compute the rank of
tuple.</span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">an idea comes to us: add some foundamental ranking features to the Gin index
structure;</span></font><pclass="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">then we can find the most relevance tuples just from index, which result in a problem that we
must</span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">add a type of indexscan and heapscan,customize plan. but PG don't support the
behaviors,.</span></font><pclass="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">As far as I know, oracle support customizing plan. My question is how can i slove it, and
whetherPG </span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">will support extending indexscan and heapscan,customizing plan in future.</span></font><p
class="MsoNormal"><fontface="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US"
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9.0pt;font-family:Arial">Thanks</span></font><p class="MsoNormal"><font face="Arial" size="1"><span lang="EN-US"
style="font-size:
9.0pt;font-family:Arial">                                                                               
--zhuxiang</span></font><pclass="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">                                                                                  Yahoo!
CN</span></font><pclass="MsoNormal"><font face="Arial" size="1"><span lang="EN-US" style="font-size: 
9.0pt;font-family:Arial">                                                                    </span></font></div>