<div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial"><br />BRIN Scan: Optimize memory allocation
infunction 'bringetbitmap'.<br />We can allocate memory for some pointer before do long loop instead of allocating <br
/>memoryin long loop.<br /><br />Before optimizing code (warm run)<br />postgres=# select count(*) from lineitem where
l_orderkey=1;<br/> count <br />-------<br /> 6<br />(1 row)<br /><br />Time: 456.219 ms<br /><br />After optimizing
code(warm run)<br />postgres=# select count(*) from lineitem where l_orderkey=1;<br /> count <br />-------<br />
6<br/>(1 row)<br /><br />Time: 349.219 ms<br /><br />The following shows the DDL of this test case.<br />CREATE TABLE
LINEITEM( L_ORDERKEY INTEGER NOT NULL,<br /> L_PARTKEY INTEGER NOT NULL,<br
/> L_SUPPKEY INTEGER NOT NULL,<br /> L_LINENUMBER INTEGER
NOTNULL,<br /> L_QUANTITY DECIMAL(15,2) NOT NULL,<br />
L_EXTENDEDPRICE DECIMAL(15,2) NOT NULL,<br /> L_DISCOUNT DECIMAL(15,2) NOT NULL,<br
/> L_TAX DECIMAL(15,2) NOT NULL,<br /> L_RETURNFLAG
CHAR(1)NOT NULL,<br /> L_LINESTATUS CHAR(1) NOT NULL,<br />
L_SHIPDATE DATE NOT NULL,<br /> L_COMMITDATE DATE NOT NULL,<br
/> L_RECEIPTDATE DATE NOT NULL,<br /> L_SHIPINSTRUCT CHAR(25)
NOTNULL,<br /> L_SHIPMODE CHAR(10) NOT NULL,<br />
L_COMMENT VARCHAR(44) NOT NULL);<br /><br />copy lineitem from '/home/jinyu/mywork/dbgen/lineitem.tbl' delimiter
'|';<br/>create index brinLineitem on lineitem using brin(L_ORDERKEY) with(pages_per_range = 1);<br /><br />Jinyu
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