Re: Declarative partitioning - Mailing list pgsql-hackers

<div dir="ltr"><br /><div class="gmail_extra"><br /><div class="gmail_quote">On Fri, Aug 5, 2016 at 5:21 PM, Robert
Haas<span dir="ltr"><<a href="mailto:robertmhaas@gmail.com" target="_blank">robertmhaas@gmail.com</a>></span>
wrote:<br/><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span
class="">OnFri, Aug 5, 2016 at 6:53 AM, Ashutosh Bapat<br /> <<a
href="mailto:ashutosh.bapat@enterprisedb.com">ashutosh.bapat@enterprisedb.<wbr/>com</a>> wrote:<br /> > The lists
forlist partitioned tables are stored as they are specified by<br /> > the user. While searching for a partition to
routetuple to, we compare it<br /> > with every list value of every partition. We might do something better<br />
>similar to what's been done to range partitions. The list of values for a<br /> > given partition can be stored
inascending/descending sorted order. Thus a<br /> > binary search can be used to check whether given row's partition
keycolumn<br /> > has same value as one in the list. The partitions can then be stored in the<br /> >
ascending/descendingorder of the least/greatest values of corresponding<br /> > partitions.<br /><br /></span>+1. 
Hereas with range partitions, we must be sure to know which<br /> opclass should be used for the comparisons.<br
/><spanclass=""><br /> > We might be able to eliminate search in a given partition if its<br /> > lowest value is
higherthan the given value or its higher value is lower<br /> > than the given value.<br /><br /></span>I don't
thinkI understand this part.<br /></blockquote></div><br clear="all" /></div><div class="gmail_extra">Consider lists
('e','i', 'f'), ('h', 'd','m') and ('l', 'b', 'a') for a list partitioned tables. I am suggesting that we arrange them
as('a','b','l'), ('d', 'h', 'm') and ('e', 'f', 'i'). If the given row (either for comparison or for inserting) has
value'c', we will search for it in ('a','b','l') but will be eliminate other two partitions since the second's
partition'slowest value is higher than 'c' and lowest values of rest of the partitions are higher than that of the
secondpartition. Without this order among the partitions, we will have to compare lowest values of all the
partitions.<br/></div><div class="gmail_extra">-- <br /><div class="gmail_signature"
data-smartmail="gmail_signature"><divdir="ltr">Best Wishes,<br />Ashutosh Bapat<br />EnterpriseDB Corporation<br />The
PostgresDatabase Company<br /></div></div></div></div>