In a Vertica database, I want to know the columns of a certain table, where the constraint "Unique" is applied.
Example:
CREATE TABLE dim1 ( c1 INTEGER,
c2 INTEGER,
c3 INTEGER,
UNIQUE (c1, c2)
);
I want to run a query where I enter the name of the table "dim1" and the result would be "c1,c2"
For more info regarding unique( Last line in the link) https://my.vertica.com/docs/7.0.x/HTML/Content/Authoring/AdministratorsGuide/Constraints/UniqueConstraints.htm
That's pretty easy to do by querying the system catalog, specifically V_CATALOG.CONSTRAINT_COLUMNS:
select column_name from V_CATALOG.CONSTRAINT_COLUMNS
where table_name = 'dim1' and constraint_type = 'u'
Related
There's total of three tables involved. one header base table, one material
base table, one staging table.
I have created the staging table with 4 columns, the values will be
updated from csv uploaded, column 1 is batch_no, column 2 is for
attribute.
>header base table(h) has batch_no and batch_id
>material base table(m) has batch_id, attr_m (empty, to be updated)
>staging table(s) has batch_no and attr_s
create table he (BATCH_ID number, BATCH_NO varchar2(30));
create table me (a6 varchar2(30), BATCH_id number);
create table s (batch_no varchar2(30), att varchar2(30));
I want to take values from attr_s and update attr_m against batch_no. How do I do that?
Here's my code, please help me fix this code, it doesn't work
update me
set a6 = (select att
from s where batch_no = (select he.batch_no
from he, s
where he.batch_no=s.batch_no))
error received:
single row subquery return multiple rows.
single row subquery return multiple rows
The update statement is applied to each individual row in ME. Therefore the assignment operation requires one scalar value to be returned from the subquery. Your subquery is returning multiple values, hence the error.
To fix this you need to further restrict the subquery so it returns one row for each row in ME. From your data model the only way to do this is with the BATCH_ID, like so:
update me
set a6 = (select att
from s where batch_no = (select he.batch_no
from he, s
where he.batch_no=s.batch_no
and he.batch_id = me.batch_id))
Such a solution will work providing that there is only one record in S which matches a given permutation of (batch_no, batch_id). As you have provided any sample data I can't verify that the above statement will actually solve your problem.
I am trying to create a table and wrote following code
create table trial as(
SELECT l2_group AS Customer
, null AS Contact
FROM ACCT_MASKED_sep17_V1) ;
It's giving me an error when I run with create table where as select query runs.
How can I get the result
You need to specify a data type for that NULL column. For example:
create table t1 as
select 1 as c1
, cast(null as number) as c2
from dual
Table created.
If as a datatype for the NULL column you choose VARCHAR2(length) datatype, the length needs to be greater than 0.
I have the below Nested table created :
create or replace TYPE access_t AS OBJECT (
AccessID VARCHAR2(50),
Eligibility char(1)
);
/
create or replace TYPE Access_tab IS TABLE OF access_t;
/
create or replace TYPE add_t AS OBJECT (
city VARCHAR2(100),
state VARCHAR2(100),
zip VARCHAR2(10),
APOINTSARRAY Access_tab )
;
/
create or replace TYPE add_tab IS TABLE OF add_t;
/
CREATE TABLE RQST_STATUS
( RQST_ID NUMBER,
ADDRESS add_tab
)
NESTED TABLE ADDRESS STORE AS RQST_STATUS_ADDRESS
( NESTED TABLE APOINTSARRAY STORE AS RQST_STATUS_AP)
;
If i need to change ADDRESS type to new_add_tab with some additional columns instead of add_tab , Can i just use ALTER TABLE .. MODIFY .. command ?
I am getting ORA-00922 or ORA-22913 errors . I cannot change the type directly because it is used somewhere else too. Also, the table is already loaded with data.
Please suggest.
You can do that but you have to alter the TYPE not the TABLE.
Check the documentation ALTER TYPE Statement: alter_method_spec
Most important is the CASCADE key word.
Examples:
ALTER TYPE access_t ADD ATTRIBUTE NEW_Eligibility INTEGER CASCADE;
ALTER TYPE access_t DROP ATTRIBUTE Eligibility CASCADE;
ALTER TYPE access_t MODIFY ATTRIBUTE AccessID VARCHAR2(100) CASCADE;
Here is a step-by-step description of my suggestion. It might not be the most elegant, but I think that it would be best for you to have something you can fully understand (as opposed to an obscure trick).
Also, and since I don't really know what kind of changes you need to do for the internal table, I'm leaving the maximal flexibility for you to do any change you may wish to do.
Let's call your table T1 that contains a columns C_T which is your internal table.
The internal table contains columns C_1, C-2 and C_3, and you want the new structure for the record to be D_1, D_2, D_3, D_4 and D_5, where the mapping is:
C_1 -> D_5,
C_2 -> D_1,
C_3 -> D_2,
{new} -> D_3,
{new} -> D_4.
Create a tempo table TEMPO_T with a column SOURCE_ROWID (varchar2(64)) and the new columns D_1,..., D5.
Write a small anonymous block having a cursor that selects the ROWID of each row of table T1 and all the records within the internal table in column C_T (order by ROWID). The result would look like (this is just an example of course):
ROWID C_1 C_2 C_2
wwereeedffff 1 a ww
wwereeedffff 2 b xx
wwereeedffff 7 l yy
ertrtrrrtrrr 5 d PP
ertrtrrrtrrr 99 h mm
...
[Note: The use of ROWID is under the assumption that you don't have a column that can serve as a unique identifier for each row in table T1; if there is such column - one defined as UNIQUE INDEX - you can use that field instead]
Having this query ready, convert it into an INSERT into the temporary table TEMPO_T along with whatever values you need to store for columns D_3 and D_4.
Now, you have a backup of the original contents of column C_T and hence can delete the column.
Now, you can update the type that defines the structure of column C_T to its new form (i.e. D_1,...,D_5) and alter table T1 by adding a column whose type is the updated one.
Finally, you can insert the contents of column C_T with that stored in the temporary table (since you already have this, I assume that you know how to implement it - inserting a table within a cell column of the outer table).
That's it.
Needless to say, I would make a backup of your data before engaging into this.
Hope this description is detailed enough to enable you to complete the task at hand.
Suppose a table called Mytable with two columns C1, and C2.
I want to have these two columns Mutually Exclusive.
I mean, if i enter value in one column C1 of this row in this table, db should not allow entry in C2 and viceversa.
in anycase, one of the column should be allowed to have data, not both(except NULL Values in both).
Is it possible either via creating triggers for this table?
ALTER TABLE mytable
ADD CONSTRAINT constraint_name CHECK (c1 is null or c2 is null)
I mean, if i enter value in one column C1 of this row in this table, db should not allow entry in C2 and viceversa.
in anycase, one of the column should be allowed to have data, not both(except NULL Values in both).
Something like that maybe ?
ALTER TABLE mytable
ADD CONSTRAINT constraint_name CHECK ((c1 is null and c2 is null) or
(c1 is not null and c2 is null) or
(c1 is null and c2 is not null))
Using a Karnaugh map or simple logic, you can rewrite that as:
ALTER TABLE mytable
ADD CONSTRAINT constraint_name CHECK (not (c1 is not null and c2 is not null))
This is is fact explicating that the only invalid combination is "having a value both for c1 and c2".
I am using Postgres 8.4. My system configuration is window 7 32 bit 4 gb ram and 2.5ghz.
I have a database in Postgres with 10 tables t1, t2, t3, t4, t5.....t10.
t1 has a primary key a sequence id which is a foreign key reference to all other tables.
The data is inserted in database (i.e. in all tables) apart from t1 all other tables have nearly 50,000 rows of data but t1 has one 1 row whose primary key is referenced from all other tables. Then I insert the 2nd row of data in t1 and again 50,000 rows with this new reference in other tables.
The issue is when I want to delete all the data entries that are present in other tables:
delete from t1 where column1='1'
This query takes nearly 10 min to execute.
I created indexes also and tried but the performance is not at all improving.
what can be done?
I have mentioned a sample schema below
CREATE TABLE t1
(
c1 numeric(9,0) NOT NULL,
c2 character varying(256) NOT NULL,
c3ver numeric(4,0) NOT NULL,
dmlastupdatedate timestamp with time zone NOT NULL,
CONSTRAINT t1_pkey PRIMARY KEY (c1),
CONSTRAINT t1_c1_c2_key UNIQUE (c2)
);
CREATE TABLE t2
(
c1 character varying(100),
c2 character varying(100),
c3 numeric(9,0) NOT NULL,
c4 numeric(9,0) NOT NULL,
tver numeric(4,0) NOT NULL,
dmlastupdatedate timestamp with time zone NOT NULL,
CONSTRAINT t2_pkey PRIMARY KEY (c3),
CONSTRAINT t2_fk FOREIGN KEY (c4)
REFERENCES t1 (c1) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE CASCADE,
CONSTRAINT t2_c3_c4_key UNIQUE (c3, c4)
);
CREATE INDEX t2_index ON t2 USING btree (c4);
Let me know if there is anything wrong with the schema.
With bigger tables and more than just two or three values, you need an index on the referenced column (t1.c1) as well as the referencing columns (t2.c4, ...).
But if your description is accurate, that can not be the cause of the performance problem in your scenario. Since you have only 2 distinct values in t1, there is just no use for an index. A sequential scan will be faster.
Anyway, I re-enacted what you describe in Postgres 9.1.9
CREATE TABLE t1
( c1 numeric(9,0) PRIMARY KEY,
c2 character varying(256) NOT NULL,
c3ver numeric(4,0) NOT NULL,
dmlastupdatedate timestamptz NOT NULL,
CONSTRAINT t1_uni_key UNIQUE (c2)
);
CREATE temp TABLE t2
( c1 character varying(100),
c2 character varying(100),
c3 numeric(9,0) PRIMARY KEY,
c4 numeric(9,0) NOT NULL,
tver numeric(4,0) NOT NULL,
dmlastupdatedate timestamptz NOT NULL,
CONSTRAINT t2_uni_key UNIQUE (c3, c4),
CONSTRAINT t2_c4_fk FOREIGN KEY (c4)
REFERENCES t1(c1) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE CASCADE
);
INSERT INTO t1 VALUES
(1,'OZGPIGp7tgp97tßp97tß97tgP?)/GP)7gf', 234, now())
,(2,'agdsOZGPIGp7tgp97tßp97tß97tgP?)/GP)7gf', 4564, now());
INSERT INTO t2
SELECT'shOahaZGPIGp7tgp97tßp97tß97tgP?)/GP)7gf'
,'shOahaZGPIGp7tgp97tßp97tß97tgP?)/GP)7gf'
, g, 2, 456, now()
from generate_series (1,50000) g
INSERT INTO t2
SELECT'shOahaZGPIGp7tgp97tßp97tß97tgP?)/GP)7gf'
,'shOahaZGPIGp7tgp97tßp97tß97tgP?)/GP)7gf'
, g, 2, 789, now()
from generate_series (50001, 100000) g
ANALYZE t1;
ANALYZE t2;
EXPLAIN ANALYZE DELETE FROM t1 WHERE c1 = 1;
Total runtime: 53.745 ms
DELETE FROM t1 WHERE c1 = 1;
58 ms execution time.
Ergo, there is nothing fundamentally wrong with your schema layout.
Minor enhancements:
You have a couple of columns defined numeric(9,0) or numeric(4,0). Unless you have a good reason to do that, you are probably a lot better off using just integer. They are smaller and faster overall. You can always add a check constraint if you really need to enforce a maximum.
I also would use text instead of varchar(n)
And reorder columns (at table creation time). As a rule of thumb, place fixed length NOT NULL columns first. Put timestamp and integer first and numeric or text last. More here..