I'm currently investigating some performance issues in a .NET/Oracle application.
I've run an oracle trace file and I have noticed that the following query is being called a lot and is using a lot of resources:
select ac.constraint_name key_name, acc.column_name key_col,1
from all_cons_columns acc, all_constraints ac
where acc.owner = ac.owner
and acc.constraint_name = ac.constraint_name
and acc.table_name = ac.table_name
and ac.constraint_type = 'P'
and ac.owner = user
and ac.table_name = :TableName
order by acc.constraint_name
I have determined that this query is not being called from the application code, could it be generated by ADO.NET? The application uses OracleCommandBuilders.
Yes, I expect is is OracleCommandBuilders that is doing that: it is finding out which columns form the primary key for the given table. It needs to do this (and other metadata selects) to generate SQL statements for your application.
Related
I am new to PostgreSQL and was wondering if there is a table which matches Oracle's user_cons_columns table which provides a column position column similar to user_cons_columns.position. Essentially, I am trying to convert the following oracle code to PostgreSQL. It attains the PK columns in order of PK definition:
Oracle Code (Original):
select a.table_name tab_name,
a.colum_name col_name,
a.position col_order
from user_cons_columns a,
user_constraints b
where a.table_name = b.table_name
and a.constraint_name = b.constraint_name
and b.constraint_type = 'P'
and a.table_name = 'some_table_name';
PostgreSQL Code (Oracle Equiv):
/* Below is my attempt at the PostgreSQL conversion */
select isc.table_name tab_name,
isc.column_name col_name,
isc.ordinal_position col_order
from pg_attribute as pga
inner join pg_class as pgc on pga.attrelid = pgc.oid
inner join pg_namespace as pgn on pgn.oid = pgc.relnamespace
inner join information_schema.columns as isc on isc.column_name = pga.attname
and isc.table_name = pgc.relname
where isc.table_name = 'sometablename';
In my PostgreSQL conversion attempt I am missing the relationship between the constraint and its position but use the column position. Which is not the same. Is there a way to do the former? Thanks in advance!
The column numbers of a constraint and their order are stored in pg_constraint.conkey; for foreign keys, the corresponding numbers of the target columns are in pg_constraint.confkey.
The description of table columns is in pg_attribute; the column number is stored in attnum.
Below is the solution that I derived thanks to the answer from #Laurenz Albe.
select isc.table_name tab_name,
isc.col_name col_name,
pgco.conkey[1] col_order
from pg_attribute as pga
inner join pg_class as pgc on pga.attrelid = pgc.oid
inner join pg_namespace as pgn on pgn.oid = pgc.relnamespace
inner join information_schema.columns as isc on isc.column = pga.attname
and isc.table_name = pgc.relname
inner join pg_constraint as pgco on pgco.conkey[1] = pga.attnum
and pgco.connamespace = pgc.relnamespace
and pgco.conrelid = pga.attrelid
where isc.table_name = 'sometablename'
and pgco.contype ='p';
Hope this is useful to someone else.
I use Yii2 a lot but normally with MySQL. This is my first time using it with Oracle. I am finding the performance quite poor though. I've done some googling around and see that although it doesn't appear that common to use Yii2 + Oracle there does seem to be people talking about it being quite slow.
I'm wondering what advice/tips/processes/packages can be employed to improve performance?
I am loading a very small table. It has 8 rows, the entire table has 4 columns. They're are 27 DB calls using 6.4MB of data, that takes about 3 seconds to run. Looking at the logs I see a lot of stuff I don't really understand:
SELECT D.CONSTRAINT_NAME, D.CONSTRAINT_TYPE, C.COLUMN_NAME, C.POSITION, D.R_CONSTRAINT_NAME, E.TABLE_NAME AS TABLE_REF, F.COLUMN_NAME AS COLUMN_REF, C.TABLE_NAME
FROM
ALL_CONS_COLUMNS C
INNER JOIN ALL_CONSTRAINTS D ON D.OWNER = C.OWNER AND D.CONSTRAINT_NAME = C.CONSTRAINT_NAME
LEFT JOIN ALL_CONSTRAINTS E ON E.OWNER = D.R_OWNER AND E.CONSTRAINT_NAME = D.R_CONSTRAINT_NAME
LEFT JOIN ALL_CONS_COLUMNS F ON F.OWNER = E.OWNER AND F.CONSTRAINT_NAME = E.CONSTRAINT_NAME AND F.POSITION = C.POSITION
and
SELECT a.column_name, a.data_type, a.data_precision, a.data_scale, a.data_length,
a.nullable, a.data_default,
( SELECT D.constraint_type
FROM ALL_CONS_COLUMNS C
inner join ALL_constraints D on D.OWNER = C.OWNER and D.constraint_name = C.constraint_name
WHERE C.OWNER = B.OWNER
and C.table_name = B.object_name
and C.column_name = A.column_name
and D.constraint_type = 'P') as Key,
com.comments as column_comment
FROM ALL_TAB_COLUMNS A
inner join ALL_OBJECTS B ON b.owner = a.owner and ltrim(B.OBJECT_NAME) = ltrim(A.TABLE_NAME)
LEFT JOIN all_col_comments com ON (A.owner = com.owner AND A.table_name = com.table_name AND A.column_name = com.column_name)
Then more stuff about triggers.
I also get errors when I try to use relations such as
Model::find()->with('relationName')->all();
I get
'ORA-01795: maximum number of expressions in a list is 1000 error.
These tables collectively have about 17k rows. There's about 11k in one table and about 7k in the other that are linked.
I'm using fk constraints as references within the tables.
Add/Use following settings in your database configurations.
'schemaCacheDuration' => 7200,
'schemaCache' => 'cache',
'enableSchemaCache' => true,
And
change YII_DEBUG from true to false and YII_ENV from dev to prod.
This will reduce unnecessary SQL executions.
Does Oracle have a tool I can use to analyze a database and help determine possible missing field relationships? We have a legacy database with 150+ tables and many relationships are missing. We could go through it by hand but an automated tool might be useful. So find things like missing foreign keys and whatnot.
I've had to do this a few times now. I find it's a very human-intelligence kind of thing - helped by running a lot of queries across both the data dictionary (e.g. EvilTeach's query), querying sample data from the columns, examining how the data is created by the application, and understanding the business requirements and user processes.
For example, in many legacy applications I find constraints (including referential integrity constraints) that are checked and implemented in the front-end application, which means the data follows the constraint (almost 100% :) ) but it's not actually constrained at the database level. Lots of fun results.
I'd be surprised if a tool could do any of this automatically and yield useful results.
This might be a good start
select column_name, table_name, data_type
from user_tab_cols
order by column_name, table_name
You could find a POSSIBLE foreign key absence if you assume that you could identify a POSSIBLE foreign key relationshinp by finding columns with equal names and data types in different tables, one of which is a primary key, and another one has no reference to that key.
You could use a query like this:
select c1.TABLE_NAME, c1.COLUMN_NAME, c2.TABLE_NAME, c2.COLUMN_NAME
from user_tab_columns c1,
user_tables at1,
user_tab_columns c2,
user_tables at2
where c1.COLUMN_NAME = c2.COLUMN_NAME
and c1.DATA_TYPE = c2.DATA_TYPE
and c1.TABLE_NAME = at1.TABLE_NAME
and c2.TABLE_NAME = at2.TABLE_NAME
and c1.TABLE_NAME != c2.TABLE_NAME
/*and c1.TABLE_NAME = 'TABLE' --check this for one table
and c1.COLUMN_NAME = 'TABLE_PK'*/
and not exists (select 1
from user_cons_columns ucc,
user_constraints uc,
user_constraints uc2,
user_cons_columns ucc2
where ucc.CONSTRAINT_NAME = uc.CONSTRAINT_NAME
and uc.TABLE_NAME = ucc.TABLE_NAME
and ucc.table_name = c1.TABLE_NAME
and ucc.column_name = c1.COLUMN_NAME
and uc.CONSTRAINT_TYPE = 'P'
and uc2.table_name = c2.TABLE_NAME
and ucc2.column_name = c2.COLUMN_NAME
and uc2.table_name = ucc2.table_name
and uc2.r_constraint_name = uc.constraint_name
and uc2.constraint_type = 'R')
This one (a sketch, optimized in no way, though) scans through all pairs of column name-type equality, and finds if one is a PK, and another one doesn't reference it.
But, and here I agree with Jeffrey, it's a very human-intelligence kind of thing, and no tool will do this for sure. In any case you'll have to do it by hand.
I've inherited a schema so don't have complete knowledge/confidence in what is there.
I have a project table with a projectId. There are a whole bunch of other tables that reference this table by project id. What I want to do is run a query to establish:
Which tables have foreign key references to the project table on
the project id
Which tables have a column called project id (in
case foreign keys are not set up).
If it was SQL Server I know how to query the metadata but how do I do this in Oracle?
1)
select table_name
from all_constraints
where r_constraint_name = [your pk/uk constraint on PROJECTS(id)]
2)
select table_name
from all_tab_columns
where column_name = 'PROJECT_ID'
You may want to add an extra predicate containing the OWNER column.
Regards,
Rob.
Ok. Here a request that give you the referenced table and column :
SELECT
c_list.CONSTRAINT_NAME as NAME,
substr(c_src.COLUMN_NAME, 1, 20) as SRC_COLUMN,
c_dest.TABLE_NAME as DEST_TABLE,
substr(c_dest.COLUMN_NAME, 1, 20) as DEST_COLUMN
FROM ALL_CONSTRAINTS c_list, ALL_CONS_COLUMNS c_src, ALL_CONS_COLUMNS c_dest
WHERE c_list.CONSTRAINT_NAME = c_src.CONSTRAINT_NAME
AND c_list.OWNER = c_src.OWNER
AND c_list.R_CONSTRAINT_NAME = c_dest.CONSTRAINT_NAME
AND c_list.OWNER = c_dest.OWNER
AND c_list.CONSTRAINT_TYPE = 'R'
AND c_src.OWNER = '<your-schema-here>'
AND c_src.TABLE_NAME = '<your-table-here>'
GROUP BY c_list.CONSTRAINT_NAME, c_src.TABLE_NAME,
c_src.COLUMN_NAME, c_dest.TABLE_NAME, c_dest.COLUMN_NAME;
Which give you something like this:
NAME |SRC_COLUMN |DEST_TABLE | DEST_COLUMN
----------------------|----------------|----------------------|-----------
CFK_RUB_FOR |FOR_URN |T03_FORMAT |FOR_URN
CFK_RUB_RUB |RUB_RUB_URN |T01_RUBRIQUE |RUB_URN
CFK_RUB_SUP |SUP_URN |T01_SUPPORT |SUP_URN
CFK_RUB_PRD |PRD_URN |T05_PRODUIT |PRD_URN
You can forget the substr() function if the result is usable without. This is not my case.
1): SELECT * FROM USER_CONSTRAINTS WHERE CONSTRAINT_NAME='R' and R_CONSTRAINT_NAME='xxx'
where xxx is the name of the primary key constraint on the project table
2): SELECT * FROM USER_TAB_COLUMNS WHERE COLUMN_NAME='PROJECT_ID'
The r_constraint_name answers here didn't seem to work for me, not sure why as I'm new to Oracle myself, but this worked:
SELECT * FROM ALL_CONSTRAINTS WHERE CONSTRAINT_NAME = '<constraint>';
My problem was slightly different. I have a table and I wanted to programatically know which other tables/columns it references.
I started with Stan's response above but this didn't give me exactly what I needed, so I came up with this, which I post here in case anyone else has my problem:
WITH src as
(SELECT ac.table_name, ac.constraint_name, accs.column_name, accs.position, ac.r_constraint_name
FROM ALL_CONSTRAINTS ac, all_cons_columns accs
WHERE ac.owner = '<owner>'
AND ac.constraint_type = 'R'
AND ac.table_name = '<src_table>'
AND accs.owner = ac.owner
AND accs.table_name = ac.table_name
AND accs.constraint_name = ac.constraint_name
ORDER BY ac.table_name, ac.constraint_name, accs.position),
dst as
(SELECT ac.table_name, ac.constraint_name, accs.column_name, accs.position
FROM ALL_CONSTRAINTS ac, all_cons_columns accs
WHERE ac.owner = '<owner>'
AND accs.owner = ac.owner
AND accs.table_name = ac.table_name
AND accs.constraint_name = ac.constraint_name
ORDER BY ac.table_name, ac.constraint_name, accs.position)
SELECT src.table_name as src_table,
dst.table_name as dst_table,
src.constraint_name as src_constraint,
src.column_name as src_column,
dst.column_name as dst_column,
src.position as position
FROM src,dst
WHERE src.r_constraint_name = dst.constraint_name
AND src.position = dst.position
Use this query.
select b.TABLE_NAME,b.CONSTRAINT_NAME ,a.COLUMN_NAME
from all_constraints b, all_cons_columns a
where r_constraint_name = 'Constraint_Name' and a.CONSTRAINT_NAME=b.CONSTRAINT_NAME;
Is there a command in oracle 9i that displays the foreign keys of a table and also the table that those foreign keys reference?
I was searching, did not find anything but i found an equivalent command that works with MySql which is SHOW CREATE TABLE
Is there an equivalent command for this within oracle's SQL?
I appreciate your response, however I thought there was a really short way of doing this like MySql.
Here's another answer: The dbms_metadata package has a function that can return the DDL for a table definition.
SELECT dbms_metadata.get_ddl('TABLE', '<table>', '<schema>') FROM dual;
This package has apparently been available since Oracle 9.2
http://download-west.oracle.com/docs/cd/B10501_01/appdev.920/a96612/d_metada.htm#1656
You could start by listing all of the constraints for the table along with any referenced constraint on other tables:
SELECT
acc.table_name
,acc.column_name
,acc.constraint_name
,ac.r_constraint_name AS referenced_constraint
FROM all_cons_columns acc
INNER JOIN all_constraints ac ON (acc.constraint_name = ac.constraint_name)
WHERE acc.table_name = UPPER('your_table_here');
If you have sensible naming conventions for your constraints it should be possible to identify which are the foreign keys, an 'FK' prefix/suffix is typical.
This may do what you want, it uses Oracle system views. I don't have an Oracle instance handy to test it, however.
SELECT fk.owner, fk.constraint_name, fk.table_name, fc.column_name,
pk.owner, pk.constraint_name, pk.table_name, pc.column_name
FROM all_constraints fk
JOIN all_cons_columns fc ON (fk.owner = fc.owner AND fk.constraint_name = fc.constraint_name)
JOIN (all_constraints pk
JOIN all_cons_columns pc ON (pk.owner = pc.owner AND pk.constraint_name = pc.constraint_name))
ON (fk.r_owner = pk.owner AND fk.r_constraint_name = pk.constraint_name
AND fc.position = pc.position)
WHERE fk.constraint_type = 'R' AND pk.constraint_type IN ('P', 'U')
AND fk.owner = '<schema>' AND fk.table_name = '<table>';
If you need the DDL for the foreign keys in the future, then here is the answer in advance :)
select
DBMS_METADATA.GET_DEPENDENT_DDL('REF_CONSTRAINT' ,atb.table_name, atb.owner)
from
all_tables atb, all_constraints ac
where
atb.owner = ac.owner and
ac.constraint_type = 'R' and
ac.table_name = atb.table_name and
atb.owner = 'YOURSCHEMA';