Save 
Join IIUG
 for   
 

Informix News
18 Nov 13 - ZDNet - Top 20 mobile skills in demand... Read
09 Sep 13 - telecompaper - Shaspa and Tatung have shown a new smart home platform at Ifa in Berlin. Powered by the IBM Informix software... Read
06 Sep 13 - IBM data magazine - Mission Accomplished - Miami, Florida will be the backdrop for the 2014 IIUG Informix Conference... Read
01 Feb 13 - IBM Data Magazine - Are your database backups safe? Lester Knutsen (IBM Champion) writes about database back up safety using "archecker"... Read
14 Nov 12 - IBM - IBM's Big Data For Smart Grid Goes Live In Texas... Read
3 Oct 12 - The Financial - IBM and TransWorks Collaborate to Help Louisiana-Pacific Corporation Achieve Supply Chain Efficiency... Read
28 Aug 12 - techCLOUD9 - Splunk kicks up a SaaS Storm... Read
10 Aug 12 - businessCLOUD9 - Is this the other half of Cloud monitoring?... Read
3 Aug 12 - IBM data management - Supercharging the data warehouse while keeping costs down IBM Informix Warehouse Accelerator (IWA) delivers superior performance for in-memory analytics processing... Read
2 Aug 12 - channelbiz - Oninit Group launches Pay Per Pulse cloud-based service... Read
28 May 12 - Bloor - David Norfolk on the recent Informix benchmark "pretty impressive results"... Read
23 May 12 - DBTA - Informix Genero: A Way to Modernize Informix 4GL Applications... Read
9 Apr 12 - Mastering Data Management - Upping the Informix Ante: Advanced Data Tools... Read
22 Mar 12 - developerWorks - Optimizing Informix database access... Read
14 Mar 12 - BernieSpang.com - International Informix User Group set to meet in San Diego... Read
1 Mar 12 - IBM Data Management - IIUG Heads West for 2012 - Get ready for sun and sand in San Diego... Read
1 Mar 12 - IBM Data Management - Running Informix on Solid-State Drives.Speed Up Database Access... Read
26 Feb 12 - BernieSpan.com - Better results, lower cost for a broad set of new IBM clients and partners... Read
24 Feb 12 - developerWorks - Informix Warehouse Accelerator: Continuous Acceleration during Data Refresh... Read
6 Feb 12 - PRLOG - Informix port delivers unlimited database scalability for popular SaaS application ... Read
2 Feb 12 - developerWorks - Loading data with the IBM Informix TimeSeries Plug-in for Data Studio... Read
1 Feb 12 - developerWorks - 100 Tech Tips, #47: Log-in to Fix Central... Read
13 Jan 12 - MC Press online - Informix Dynamic Server Entices New Users with Free Production Edition ... Read
11 Jan 12 - Computerworld - Ecologic Analytics and Landis+Gyr -- Suitors Decide to Tie the Knot... Read
9 Jan 12 - planetIDS.com - DNS impact on Informix / Impacto do DNS no Informix... Read
8 Sep 11 - TMCnet.com - IBM Offers Database Solution to Enable Smart Meter Data Capture... Read
1 Aug 11 - IBM Data Management Magazine - IIUG user view: Happy 10th anniversary to IBM and Informix... Read
8 Jul 11 - Database Trends and Applications - Managing Time Series Data with Informix... Read
31 May 11 - Smart Grid - The meter data management pitfall utilities are overlooking... Read
27 May 11 - IBM Data Management Magazine - IIUG user view: Big data, big time ( Series data, warehouse acceleration, and 4GLs )... Read
16 May 11 - Business Wire - HiT Software Announces DBMoto for Enterprise Integration, Adds Informix. Log-based Change Data Capture... Read
21 Mar 11 - Yahoo! Finance - IBM and Cable&Wireless Worldwide Announce UK Smart Energy Cloud... Read
14 Mar 11 - MarketWatch - Fuzzy Logix and IBM Unveil In-Database Analytics for IBM Informix... Read
11 Mar 11 - InvestorPlace - It's Time to Give IBM Props: How many tech stocks are up 53% since the dot-com boom?... Read
9 Mar 11 - DBTA - Database Administration and the Goal of Diminishing Downtime... Read
2 Feb 11 - DBTAs - Informix 11.7 Flexible Grid Provides a Different Way of Looking at Database Servers... Read
27 Jan 11 - exactsolutions - Exact to Add Informix Support to Database Replay, SQL Monitoring Solutions... Read
25 Jan 11 - PR Newswire - Bank of China in the UK Works With IBM to Become a Smarter, Greener Bank... Read
12 Oct 10 - Database Trends and Applications - Informix 11.7: The Beginning of the Next Decade of IBM Informix... Read
20 Sep 10 - planetIDS.com - ITG analyst paper: Cost/Benefit case for IBM Informix as compared to Microsoft SQL Server... Read
20 Jul 10 - IBM Announcements - IBM Informix Choice Edition V11.50 helps deploy low-cost scalable and reliable solutions for Apple Macintosh and Microsoft Windows... Read
20 Jul 10 - IBM Announcements - Software withdrawal: Elite Support for Informix Ultimate-C Edition... Read
24 May 10 - eWeek Europe - IBM Supplies Database Tech For EU Smart Grid... Read
23 May 10 - SiliconIndia - IBM's smart metering system allows wise use of energy... Read
21 May 10 - CNET - IBM to help people monitor energy use... Read
20 May 10 - ebiz - IBM Teams With Hildebrand To Bring Smart Metering To Homes Across Britain... Read
19 May 10 - The New Blog Times - Misurare il consumo energetico: DEHEMS è pronto... Read
19 May 10 - ZDNet - IBM software in your home? Pact enables five-city smart meter pilot in Europe... Read
17 March 10 - ZDNet (blog) David Morgenstern - TCO: New research finds Macs in the enterprise easier, cheaper to manage than... Read
17 March 2010 - Virtualization Review - ...key components of Big Blue's platform to the commercial cloud such as its WebSphere suite of application ser vers and its DB2 and Informix databases... Read
10 February 2010 - The Wall Street Journal - International Business Machines is expanding an initiative to win over students and professors on its products. How do they lure the college crowd?... Read


End of Support Dates

IIUG on Facebook IIUG on Twitter

[ View Thread ] [ Post Response ] [ Return to Index ] [ Read Prev Msg ] [ Read Next Msg ]

IDS Forum

Poorly Optimized SQL

Posted By: MICHAEL HOFFMAN
Date: Tuesday, 6 August 2013, at 12:14 p.m.

Hi All,
Can someone explain why Informix is going out to lunch on the 'set' subquery?
The accessed table is the same one as in the main query. Almost immediately prior to running this statement, that table was "update statistics low drop distributions" and "update statistics high on v_id", so stats should be fine.

Running Informix 11.50.FC6 on Solaris 10.

I'm interested in *why* the Optimizer is basically ignoring the index on 'm1' and taking so long to run that subquery (as opposed to configuration changes to make it run faster; there are plenty of tuning issues to be addressed).

v_inq is a permanent table with 8000 rows, residing in one dbspace. (v_id integer, primary key)
mthly_info (s / s1) is a temp table created by selecting from an external table, 3M rows. (v_id varchar(50), indexed)
mthly_updts (m) is a very small temp table holding a subset of ids and statuses, 9365 rows. (v_id varchar(50))

One Temp dbspace configured (I know, but this is a dev box, short on space).
PDQ Priority = 100 -- not in use, so not relevant.

I would expect the Query to run in this fashion (please correct if I'm wrong):
1) Select v_ids between tables 'm' and 's'.
2) Update 'v_inq' records for those v_ids,
3) pulling associated cancel_dt from 's1' matching by v_id.

So, why is the optimizer hitting s1 *49.8 Billion* times? (see Explain Plan)
Even if it sequentially scanned s1 for every v_inq record, that is only 24B reads (8K * 3M).

Thanks,
Mike

Here is the Explain Plan:
QUERY: (OPTIMIZATION TIMESTAMP: 08-05-2013 16:17:20)
------
update v_inq
set reg_cncl_dt = (select unique cancel_dt from mthly_info s1

where s1.v_id = to_char(v_inq.v_id))
where v_id in (
select unique m.v_id::integer from mthly_updts m, mthly_info s

where m.v_id = s.v_id

and m.typ = 'E' and m.cit = 'U'

and s.status = 'C' )
and vg_stat <> 'C'

Estimated Cost: 546
Estimated # of Rows Returned: 1
Maximum Threads: 0

1) devdba.v_inq: INDEX PATH

Filters: devdba.v_inq.vg_stat != 'C'

(1) Index Name: devdba.vi_vid_idx

Index Keys: v_id (Parallel, fragments: ALL)

Lower Index Filter: devdba.v_inq.v_id = ANY <subquery>

Subquery:

---------

Estimated Cost: 122589

Estimated # of Rows Returned: 1

Maximum Threads: 1

1) devdba.s1: INDEX PATH

(1) Index Name: mthly_info_idx1

Index Keys: v_id (Key-First) (Parallel, fragments: ALL)

Index Key Filters: (devdba.s1.v_id = TO_CHAR (devdba.v_inq.v_id ) )

Subquery:

---------

Estimated Cost: 544

Estimated # of Rows Returned: 1

Maximum Threads: 5

1) devdba.m: SEQUENTIAL SCAN

Filters: (devdba.m.cit = 'U' AND devdba.m.typ = 'E' )

2) devdba.s: INDEX PATH

Filters: devdba.s.status = 'C'

(1) Index Name: mthly_info_idx1

Index Keys: v_id (Parallel, fragments: ALL)

Lower Index Filter: devdba.m.v_id = devdba.s.v_id
NESTED LOOP JOIN

Query statistics:
-----------------

Table map :
----------------------------
Internal name Table name
----------------------------
t1 voter_inquiry

type table rows_prod est_rows rows_scan time est_cost
-------------------------------------------------------------------
scan t1 179 1 188 00:00.24 547

Subquery statistics:
--------------------

Table map :
----------------------------
Internal name Table name
----------------------------
t1 m
t2 s

type table rows_prod est_rows rows_scan time est_cost
-------------------------------------------------------------------
scan t1 997 94 9365 00:00.01 411

type table rows_prod est_rows rows_scan time est_cost
-------------------------------------------------------------------
scan t2 188 275859 997 00:00.25 1

type rows_prod est_rows time est_cost
-------------------------------------------------
nljoin 188 9 00:00.32 545

type rows_sort est_rows rows_cons time
-------------------------------------------------
sort 183 1 188 00:00.10

Subquery statistics:
--------------------

Table map :
----------------------------
Internal name Table name
----------------------------
t1 s1

type table rows_prod est_rows rows_scan time est_cost
-------------------------------------------------------------------
scan t1 16110 1 49808753010 10155:54.95 122590

type rows_sort est_rows rows_cons time
-------------------------------------------------
sort 179 1 179 113:03.41

Messages In This Thread

[ View Thread ] [ Post Response ] [ Return to Index ] [ Read Prev Msg ] [ Read Next Msg ]

IDS Forum is maintained by Administrator with WebBBS 5.12.