Weekly script #3 unix_usr.sql

I use this one all the time. You have a high usage unix PID that is an Oracle Process. The script will take your defined pid and lookup the relating SQL and database user details to help you figure out the root cause.


set serveroutput on size 50000
set echo off feed off veri off
accept 1 prompt 'Enter Unix process id: '

DECLARE
v_sid number;
s sys.v_$session%ROWTYPE;
p sys.v_$process%ROWTYPE;
BEGIN
begin
select sid into v_sid
from sys.v_$process p, sys.v_$session s
where p.addr = s.paddr
and (p.spid = &&1
or s.process = '&&1');
exception
when no_data_found then
dbms_output.put_line('Unable to find process id &&1!!!');
return;
when others then
dbms_output.put_line(sqlerrm);
return;
end;

select * into s from sys.v_$session where sid = v_sid;
select * into p from sys.v_$process where addr = s.paddr;

dbms_output.put_line('=====================================================================');
dbms_output.put_line('SID/Serial : '|| s.sid||','||s.serial#);
dbms_output.put_line('Foreground : '|| 'PID: '||s.process||' - '||s.program);
dbms_output.put_line('Shadow : '|| 'PID: '||p.spid||' - '||p.program);
dbms_output.put_line('Terminal : '|| s.terminal || '/ ' || p.terminal);
dbms_output.put_line('OS User : '|| s.osuser||' on '||s.machine);
dbms_output.put_line('Ora User : '|| s.username);
dbms_output.put_line('Status Flags: '|| s.status||' '||s.server||' '||s.type);
dbms_output.put_line('Tran Active : '|| nvl(s.taddr, 'NONE'));
dbms_output.put_line('Login Time : '|| to_char(s.logon_time, 'Dy HH24:MI:SS'));
dbms_output.put_line('Last Call : '|| to_char(sysdate-(s.last_call_et/60/60/24), 'Dy HH24:MI:SS') || ' - ' || to_char(s.last_call_et/60, '990.0') || ' min');
dbms_output.put_line('Lock/ Latch : '|| nvl(s.lockwait, 'NONE')||'/ '||nvl(p.latchwait, 'NONE'));
dbms_output.put_line('Latch Spin : '|| nvl(p.latchspin, 'NONE'));

dbms_output.put_line('Current SQL statement:');
for c1 in ( select * from sys.v_$sqltext
where HASH_VALUE = s.sql_hash_value order by piece) loop
dbms_output.put_line(chr(9)||c1.sql_text);
end loop;

dbms_output.put_line('Previous SQL statement:');
for c1 in ( select * from sys.v_$sqltext
where HASH_VALUE = s.prev_hash_value order by piece) loop
dbms_output.put_line(chr(9)||c1.sql_text);
end loop;

dbms_output.put_line('Session Waits:');
for c1 in ( select * from sys.v_$session_wait where sid = s.sid) loop
dbms_output.put_line(chr(9)||c1.state||': '||c1.event);
end loop;

-- dbms_output.put_line('Connect Info:');
-- for c1 in ( select * from sys.v_$session_connect_info where sid = s.sid) loop
-- dbms_output.put_line(chr(9)||': '||c1.network_service_banner);
-- end loop;

dbms_output.put_line('Locks:');
for c1 in ( select /*+ ordered */
decode(l.type,
-- Long locks
'TM', 'DML/DATA ENQ', 'TX', 'TRANSAC ENQ',
'UL', 'PLS USR LOCK',
-- Short locks
'BL', 'BUF HASH TBL', 'CF', 'CONTROL FILE',
'CI', 'CROSS INST F', 'DF', 'DATA FILE ',
'CU', 'CURSOR BIND ',
'DL', 'DIRECT LOAD ', 'DM', 'MOUNT/STRTUP',
'DR', 'RECO LOCK ', 'DX', 'DISTRIB TRAN',
'FS', 'FILE SET ', 'IN', 'INSTANCE NUM',
'FI', 'SGA OPN FILE',
'IR', 'INSTCE RECVR', 'IS', 'GET STATE ',
'IV', 'LIBCACHE INV', 'KK', 'LOG SW KICK ',
'LS', 'LOG SWITCH ',
'MM', 'MOUNT DEF ', 'MR', 'MEDIA RECVRY',
'PF', 'PWFILE ENQ ', 'PR', 'PROCESS STRT',
'RT', 'REDO THREAD ', 'SC', 'SCN ENQ ',
'RW', 'ROW WAIT ',
'SM', 'SMON LOCK ', 'SN', 'SEQNO INSTCE',
'SQ', 'SEQNO ENQ ', 'ST', 'SPACE TRANSC',
'SV', 'SEQNO VALUE ', 'TA', 'GENERIC ENQ ',
'TD', 'DLL ENQ ', 'TE', 'EXTEND SEG ',
'TS', 'TEMP SEGMENT', 'TT', 'TEMP TABLE ',
'UN', 'USER NAME ', 'WL', 'WRITE REDO ',
'TYPE='||l.type) type,
decode(l.lmode, 0, 'NONE', 1, 'NULL', 2, 'RS', 3, 'RX',
4, 'S', 5, 'RSX', 6, 'X',
to_char(l.lmode) ) lmode,
decode(l.request, 0, 'NONE', 1, 'NULL', 2, 'RS', 3, 'RX',
4, 'S', 5, 'RSX', 6, 'X',
to_char(l.request) ) lrequest,
decode(l.type, 'MR', o.name,
'TD', o.name,
'TM', o.name,
'RW', 'FILE#='||substr(l.id1,1,3)||
' BLOCK#='||substr(l.id1,4,5)||' ROW='||l.id2,
'TX', 'RS+SLOT#'||l.id1||' WRP#'||l.id2,
'WL', 'REDO LOG FILE#='||l.id1,
'RT', 'THREAD='||l.id1,
'TS', decode(l.id2, 0, 'ENQUEUE', 'NEW BLOCK ALLOCATION'),
'ID1='||l.id1||' ID2='||l.id2) objname
from sys.v_$lock l, sys.obj$ o
where sid = s.sid
and l.id1 = o.obj#(+) ) loop
dbms_output.put_line(chr(9)||c1.type||' H: '||c1.lmode||' R: '||c1.lrequest||' - '||c1.objname);
end loop;

dbms_output.put_line('=====================================================================');

END;
/

undef 1

Perfect Datawarehouse

This post will outline the parameters and considerations that need to be made in order to create a basic data warehouse for any need.

With any data warehouse the aim is clear – The aim is to gather and process large amounts of data in the shortest space of time. If you can achieve this the the goal of a data warehouse has been reached.

Note that these parameters are not set in stone and some may need to be tweaked to fit your respective environment.

It is key to plan your data warehouse approximately from the word go. During these initial steps  CPU and I/O are key failing to gauge these correctly will result in poor performance later on when you load data or look to scale out you DW. Tuning and changing parameters can only do so much until the problem become under performing hardware.

While no environment is the same a good starting point as per Oracles recommendations are 200MB/s of I/O throughput per CPU core. Also the link between should be fiber channel to accommodate.

db_block_checksum – TRUE
db_file_multiblock_read_count – 0
db_block_size – 32k
dml_locks -1000
job_queue_processes – 2
log_buffer – 10485760 (10G)
log_checkpoint_interval -100000
log_checkpoint_timeout – 3600
Open_cursors – 1000
Processes – 500 (max number of conccurent users x2)
sessions – 1000 (Num of processes x2)
session_cached_cursors – 500
shared_pool_reserved_size – 40mb
shared_pool_size – 400mb or 0 for oracle to manage
sga_target -2G
sga_max_size – 2200mb
undo_retention – 90000

Statistics gathering is a key part to a data warehouse. Gathering statistics allows the DW to make educated decisions on the best explain plan thus reducing the query run time. Tuning a data warehouse with start schema enables is relativity simple a without diving to much into every option a simple configuration would be to create Bitmap indexes of each foreign keys columns in the fact table or tables.

dbms_stats.gather_schema_stats – GATHER AUTO
STAR_TRANSFORMATION_ENABLED – TRUE  (If using Star Schema)
OPTIMIZER_MODE = ALL_ROWS
QUERY_REWRITE_ENABLED = TRUE
QUERY_REWRITE_INTEGRITY – TRUSTED
HASH_JOIN_ENABLED – true
always_anti_join = hash
always_semi_join = hash

In order to take full advantage of the hardware provided I would recommend using parallel execution of queries.

In regards to parallel execution a good starting point is below:

Objects smaller than 200 MB should not use any parallelism

Objects between 200 MB and 5GB should use a DOP of 4

Objects beyond 5GB use a DOP of 32

These sizing should be changes to fit the hardware restrictions.

parallel_automatic_tuning = true

parallel_threads_per_cpu = Number of cores per cpu x2
cpu_count = xx – make sure correct

Until next time.