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https://issues.apache.org/jira/browse/DERBY-6045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13588052#comment-13588052
]
Mamta A. Satoor edited comment on DERBY-6045 at 2/27/13 8:29 PM:
-----------------------------------------------------------------
I am copying the JDBC program which will show that on trunk, SELECT query with
OR clause does not use index scan if there is following constraint defined on
the table(haven't tried 10.9 codeline because my 10.9 client has pending work
from other jira). 10.8 and 10.7 codelines continue to use index scan even with
the following constraint defined on the table.
s.execute("ALTER TABLE variable_term ADD CONSTRAINT
kb_variable_term_variable_name_unique UNIQUE (var_name, var_type)");
In trunk, if I comment out the code for creating
kb_variable_term_variable_name_unique, the SELECT query with OR clause starts
using index scan. NOTE that table has 10K rows in it. To run the program, do
following and then look at derby.log for the query plans for the SELECT queries
java -Dderby.language.logQueryPlan=true MamtaJDBC
public class MamtaJDBC {
public static void main(String[] args) {
try {
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Connection conn = DriverManager
.getConnection("jdbc:derby:db1;create=true");
Statement s = conn.createStatement();
s.execute("CREATE TABLE VARIABLE_TERM (" +
" term_id int NOT NULL," +
" var_name VARCHAR(1024) NOT NULL,"+
" var_type SMALLINT NOT NULL, "+
" kb_status INTEGER NOT NULL )");
s.execute("ALTER TABLE variable_term ADD CONSTRAINT
kb_variable_term_term_id_pk PRIMARY KEY (term_id)");
s.execute("ALTER TABLE variable_term ADD CONSTRAINT
kb_variable_term_variable_name_unique UNIQUE (var_name, var_type)");
int count = 10000;
for (int i = 0; i < count; i++) {
s.execute("INSERT INTO VARIABLE_TERM VALUES (" + i + ",
\'?var"+i+"\',"+ (((i %2) == 0) ? 1 : 4)+",1)");
}
s.execute("SELECT * FROM VARIABLE_TERM WHERE TERM_ID = 30");
s.execute("SELECT * FROM VARIABLE_TERM WHERE (TERM_ID = 1) OR
(TERM_ID =39) OR (TERM_ID = 24)");
} catch (SQLException se) {
while (se != null) {
System.out.println("SQLState=" + se.getSQLState()
+ se.getMessage());
se.printStackTrace();
se = se.getNextException();
}
} catch (Exception ex) {
System.out.println("exception " + ex.getMessage());
} finally {
System.exit(0);
}
}
}
was (Author: mamtas):
I am copying the JDBC program which will show that on trunk, SELECT query
with OR clause does not use index scan if there is following constraint defined
on the table(haven't tried 10.9 codeline because my 10.9 client has pending
work from other jira). 10.8 and 10.7 codelines continue to use index scan even
with the following constraint defined on the table.
s.execute("ALTER TABLE variable_term ADD CONSTRAINT
kb_variable_term_variable_name_unique UNIQUE (var_name, var_type)");
In trunk, if I comment out the code for creating
kb_variable_term_variable_name_unique, the SELECT query with OR clause starts
using index scan. NOTE that table has 10K rows in it. To run the program, do
following and then look at derby.log for the query plans for the SELECT queries
java -Dderby.language.logQueryPlan=true
org.apache.derbyTesting.functionTests.tests.lang.MamtaJDBC
public class MamtaJDBC {
public static void main(String[] args) {
try {
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Connection conn = DriverManager
.getConnection("jdbc:derby:db1;create=true");
Statement s = conn.createStatement();
s.execute("CREATE TABLE VARIABLE_TERM (" +
" term_id int NOT NULL," +
" var_name VARCHAR(1024) NOT NULL,"+
" var_type SMALLINT NOT NULL, "+
" kb_status INTEGER NOT NULL )");
s.execute("ALTER TABLE variable_term ADD CONSTRAINT
kb_variable_term_term_id_pk PRIMARY KEY (term_id)");
s.execute("ALTER TABLE variable_term ADD CONSTRAINT
kb_variable_term_variable_name_unique UNIQUE (var_name, var_type)");
int count = 10000;
for (int i = 0; i < count; i++) {
s.execute("INSERT INTO VARIABLE_TERM VALUES (" + i + ",
\'?var"+i+"\',"+ (((i %2) == 0) ? 1 : 4)+",1)");
}
s.execute("SELECT * FROM VARIABLE_TERM WHERE TERM_ID = 30");
s.execute("SELECT * FROM VARIABLE_TERM WHERE (TERM_ID = 1) OR
(TERM_ID =39) OR (TERM_ID = 24)");
} catch (SQLException se) {
while (se != null) {
System.out.println("SQLState=" + se.getSQLState()
+ se.getMessage());
se.printStackTrace();
se = se.getNextException();
}
} catch (Exception ex) {
System.out.println("exception " + ex.getMessage());
} finally {
System.exit(0);
}
}
}
> in list multi-probe by primary key not chosen on tables with >256 rows
> ----------------------------------------------------------------------
>
> Key: DERBY-6045
> URL: https://issues.apache.org/jira/browse/DERBY-6045
> Project: Derby
> Issue Type: Bug
> Components: Store
> Affects Versions: 10.9.1.0, 10.10.0.0
> Environment: Linux Debian 6.0.5
> Reporter: Tony Brusseau
>
> I have a table with a long integer primary key field and 11 million rows. I
> seem to be unable to load large chunks of rows via id in a reasonably
> efficient manner.
> 1. If I do individual lookups via the primary key, then a fast indexed
> lookup occurs. However, if I do large numbers of such queries, then the time
> is overwhelmed by round-trip overhead which makes everything incredibly slow.
> 2. If I use a single query with a disjunction of the primary keys of
> interest, then a table scan is performed (even if the clause only contains
> 1-3 items), which walks over 11 million rows...incredibly inefficient.
> 3. If I use an IN clause, then a table scan is performed (even if the
> clause only contains 1-3 items), which walks over 11 million
> rows...incredibly inefficient.
> I'm guessing that this might have something to do with the fact that I'm
> using large integers and really big numbers that don't start anywhere at or
> about 1 for my keys. Could this possibly be confusing the optimizer?
> Here are the unlimited query plans for the 3 cases that I enumerated:
> *********************************************************************************************
> [EL Fine]: 2013-01-17
> 11:09:53.384--ServerSession(582235416)--Connection(1430986883)--Thread(Thread["Initial
> Lisp Listener",5,SubL Thread Group])--SELECT TERM_ID, ARG0, ARG1, ARG2,
> ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM
> KB.FORMULA_TERM WHERE (TERM_ID = ?)
> bind => [2251799814033500]
> Thu Jan 17 11:09:53 CST 2013 Thread["Initial Lisp Listener",5,SubL Thread
> Group] (XID = 4711079), (SESSIONID = 3), SELECT TERM_ID, ARG0, ARG1, ARG2,
> ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM
> KB.FORMULA_TERM WHERE (TERM_ID = ?) ******* Project-Restrict ResultSet (3):
> Number of opens = 1
> Rows seen = 1
> Rows filtered = 0
> restriction = false
> projection = true
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1.00
> optimizer estimated cost: 6.59
> Source result set:
> Index Row to Base Row ResultSet for FORMULA_TERM:
> Number of opens = 1
> Rows seen = 1
> Columns accessed from heap = {1, 2, 3, 4, 5, 6, 7, 8}
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> optimizer estimated row count: 1.00
> optimizer estimated cost: 6.59
> Index Scan ResultSet for FORMULA_TERM using constraint
> KB_FORMULA_TERM_TERM_ID_PK at read committed isolation level using share row
> locking chosen by the optimizer
> Number of opens = 1
> Rows seen = 1
> Rows filtered = 0
> Fetch Size = 1
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> next time in milliseconds/row = 0
> scan information:
> Bit set of columns fetched=All
> Number of columns fetched=2
> Number of deleted rows visited=0
> Number of pages visited=3
> Number of rows qualified=1
> Number of rows visited=1
> Scan type=btree
> Tree height=-1
> start position:
> >= on first 1 column(s).
> Ordered null semantics on the following
> columns:
> stop position:
> > on first 1 column(s).
> Ordered null semantics on the following
> columns:
> qualifiers:
> None
> optimizer estimated row count: 1.00
> optimizer estimated cost: 6.59
> [EL Fine]: 2013-01-17
> 11:01:00.732--ServerSession(1237006689)--Connection(927179828)--Thread(Thread["Initial
> Lisp Listener",5,SubL Thread Group])--SELECT TERM_ID, ARG0, ARG1, ARG2,
> ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM
> KB.FORMULA_TERM WHERE (((TERM_ID = ?) OR (TERM_ID = ?)) OR (TERM_ID = ?))
> bind => [2251799814033500, 2251799814033501, 2251799814033499]
> Thu Jan 17 11:01:10 CST 2013 Thread["Initial Lisp Listener",5,SubL Thread
> Group] (XID = 4711078), (SESSIONID = 3), SELECT TERM_ID, ARG0, ARG1, ARG2,
> ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM
> KB.FORMULA_TERM WHERE (((TERM_ID = ?) OR (TERM_ID = ?)) OR (TERM_ID = ?))
> ******* Project-Restrict ResultSet (3):
> Number of opens = 1
> Rows seen = 3
> Rows filtered = 0
> restriction = false
> projection = true
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Project-Restrict ResultSet (2):
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 11767295
> restriction = true
> projection = false
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Table Scan ResultSet for FORMULA_TERM at read committed
> isolation level using instantaneous share row locking chosen by the optimizer
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 0
> Fetch Size = 16
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> next time in milliseconds/row = 0
> scan information:
> Bit set of columns fetched=All
> Number of columns fetched=9
> Number of pages visited=34358
> Number of rows qualified=11767298
> Number of rows visited=11767298
> Scan type=heap
> start position:
> null
> stop position:
> null
> qualifiers:
> None
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> [EL Fine]: 2013-01-17
> 11:27:00.627--ServerSession(1237006689)--Connection(1688096771)--Thread(Thread["Initial
> Lisp Listener",5,SubL Thread Group])--SELECT TERM_ID, ARG0, ARG1, ARG2,
> ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM
> KB.FORMULA_TERM WHERE (TERM_ID IN (?,?,?))
> bind => [2251799814033500, 2251799814033501, 2251799814033499]
> Thu Jan 17 11:47:26 CST 2013 Thread["Initial Lisp Listener",5,SubL Thread
> Group] (XID = 4711080), (SESSIONID = 3), SELECT TERM_ID, ARG0, ARG1, ARG2,
> ARG3, FORMULA_HASH, FORMULA_LENGTH, FORMULA_TYPE, KB_STATUS FROM
> KB.FORMULA_TERM WHERE (TERM_ID IN (?,?,?)) ******* Project-Restrict ResultSet
> (3):
> Number of opens = 1
> Rows seen = 3
> Rows filtered = 0
> restriction = false
> projection = true
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Project-Restrict ResultSet (2):
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 11767295
> restriction = true
> projection = false
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> restriction time (milliseconds) = 0
> projection time (milliseconds) = 0
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
> Source result set:
> Table Scan ResultSet for FORMULA_TERM at read committed
> isolation level using instantaneous share row locking chosen by the optimizer
> Number of opens = 1
> Rows seen = 11767298
> Rows filtered = 0
> Fetch Size = 16
> constructor time (milliseconds) = 0
> open time (milliseconds) = 0
> next time (milliseconds) = 0
> close time (milliseconds) = 0
> next time in milliseconds/row = 0
> scan information:
> Bit set of columns fetched=All
> Number of columns fetched=9
> Number of pages visited=34358
> Number of rows qualified=11767298
> Number of rows visited=11767298
> Scan type=heap
> start position:
> null
> stop position:
> null
> qualifiers:
> None
> optimizer estimated row count: 1176730.30
> optimizer estimated cost: 5931065.54
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