Re: [Monetdb-developers] Data integrity bug

Ross, I forgot to answer one of your questions. Although my web service can delete data, running a delete doesn't seen to be involved with this issue. To make a long story short it seems everything is okay until I add a column during an update. -Carl On Mon, Oct 6, 2008 at 2:50 PM, Carl Nobile wrote:

Yes, the same is true with my situation. It can work fine 3 or 4 times in a row then select from where equals just stops returning any data.

-Carl

On Mon, Oct 6, 2008 at 2:45 PM, Ross Bates wrote:

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Something definitely going on with the table stats, I am seeing the same strange behavior in that it doesn't occur on a consistent basis.

I have finally been able to recreate it using the following steps. (also see my notes that follow)

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CREATE TABLE "sobi"."table1" ( cid integer, p varchar(100), c varchar(100), lf integer, rt integer, lvl integer )

insert into sobi.table1 values (1,'foo','bar',9,12,1) insert into sobi.table1 values (1,'boo','blah',13,22,1)

CREATE TABLE "sobi"."table2" ( p varchar(100), c varchar(100), lf integer, rt integer, lvl integer )

insert into sobi.table2(p,c) (select p,c from sobi.table1)

select * from sobi.table2

select * from sobi.table2 where p = 'foo'

delete from sobi.table2

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It might happen right away - or it might take 5-10 times, but if you iterate over the insert > select > delete statements eventually the [p = 'foo'] select will stop returning rows.

On Mon, Oct 6, 2008 at 1:24 PM, Carl Nobile wrote:

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Ross,

I have written a web service in Python that sets on top of MonetDB it is somewhat complicated, but I'll try to explain it below. There are only three tables in the schema and one view over sys.tables and sys.columns.

BUSINESS_UNIT BUSINESS_USER_COLUMN_STATS BUSINESS_USER_PROFILE BUSINESS_USER_PROFILE_COLUMNS

1) START TRANSACTION

2) Check if record exists to determine if an UPDATE or an INSERT needs to be done. (SELECT count(*) FROM "BUSINESS_USER_PROFILE" WHERE "USER_ID"=%(USER_ID)s AND "BUSINESS_ID"=%(BUSINESS_ID)s)

3) If an INSERT then check if the BUSINESS_UNIT is present. SELECT count(*) FROM "BUSINESS_UNIT" WHERE "BUSINESS_ID"=%(BUSINESS_ID)s

4) If UPDATE see item 13

5) If INSERT then: INSERT INTO "BUSINESS_UNIT" ("BUSINESS_ID", "CREATE_DT", "CREATE_CID") VALUES (%(BUSINESS_ID)s, %(CREATE_DT)s, %(CREATE_CID)s

6) Look to see if any new columns need to be added to BUSINESS_USER_PROFILE by checking the view, if yes then: ALTER TABLE "BUSINESS_USER_PROFILE" ADD COLUMN "%s" VARCHAR(240) NULL

7) Commit then START TRANSACTION

8) INSERT the record into the BUSINESS_USER_PROFILE table (the two %s constructs could be any number of columns and values): INSERT INTO "BUSINESS_USER_PROFILE" (%s) VALUES (%s)

9) Check to see if the column needs to be inserted or updated to the stats table: SELECT "COLUMN_NAME" FROM "BUSINESS_USER_COLUMN_STATS"

10) Check the view again to see if the column already exists.

11) If INSERT: INSERT INTO "BUSINESS_USER_COLUMN_STATS" ("COLUMN_NAME", "BUSINESS_ID", "LAST_UPDT_DT", "LAST_UPDT_CID") VALUES (%(COLUMN_NAME)s, %(BUSINESS_ID)s, %(LAST_UPDT_DT)s, %(LAST_UPDT_CID)s)

12) If UPDATE: UPDATE "BUSINESS_USER_COLUMN_STATS" SET "BUSINESS_ID"=%(BUSINESS_ID)s, "LAST_UPDT_DT"=%(LAST_UPDT_DT)s, "LAST_UPDT_CID"=%(LAST_UPDT_CID)s WHERE "COLUMN_NAME"=%(COLUMN_NAME)s

13) Do 6 and 7 above.

14) UPDATE the record in the BUSINESS_USER_PROFILE table (the two %s constructs could be any number of columns or conditions): 'UPDATE "BUSINESS_USER_PROFILE" SET %s WHERE %s

15) Do 9, 10, 11, and 12

OK this may be over kill, but I had to think through the process myself before I could answer your question. Any select after doing a sequence of six inserts and six updates would usually cause the issue. The operative word is 'usually', because sometimes it would work flawlessly.

-Carl

On Mon, Oct 6, 2008 at 1:23 PM, Ross Bates wrote:

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Carl - this bug continues to bother me as well as I can't reproduce the exact steps.

Does your application populate the table in question using sql like this?

insert into foo(col1,col2) (select col1,col2 from bar)

Also, do you run any delete statements before populating the data?

I was thinking that the bug was related to the addition/deletion of columns, but it appears to show up more often after a series of insert/delete statements which follow my alter/create table statements.

On Sun, Oct 5, 2008 at 4:19 PM, Stefan de Konink wrote:

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Ross Bates schreef:

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Stefan - what is occurring in the alignment bug you are referring to?

I had an issue before that occured after I had added an index (that in MonetDB terms shouldn't do anything), where I was able to make mserver5 crash on a string comparison.

But I know that this was fixed even before I had reported it.

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------------------------------------------------------------------------------- Carl J. Nobile (Software Engineer) carl.nobile@gmail.com

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------------------------------------------------------------------------------- Carl J. Nobile (Software Engineer) carl.nobile@gmail.com

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-- ------------------------------------------------------------------------------- Carl J. Nobile (Software Engineer) carl.nobile@gmail.com -------------------------------------------------------------------------------