I need to fetch all tables in a particular Postgres database using node. But not finding any way to achieve that. Is there any way to get that?
For example, suppose I have a database named 'TestDatabase' it contains 4 tables( just assume it can have less or more) Person, Company, Clothes, Animal.
I need to get the name of all of them using node.
I am also using node-postgres ('pg') to connect with the database.
As an alternative you can use information_schema. It is not better then the pg_* objects in the system catalog but is standardized and more portable. Here it is:
select table_schema||'.'||table_name as table_fullname
from information_schema."tables"
where table_type = 'BASE TABLE'
and table_schema not in ('pg_catalog', 'information_schema');
The system objects have been filtered by this expression
table_schema not in ('pg_catalog', 'information_schema')
You can further modify it to only include schemas that you need.
This is a generic solution. Use the query below:
SELECT
relname
FROM
pg_class
WHERE
relkind = 'r';
pg_class is the system catalog that holds information on table like objects. Hence the need to restrict relkind to 'r'. This will include all table types. To further restrict see relpersistence at link below.
https://www.postgresql.org/docs/current/catalog-pg-class.html
Looking at the following lines of code:
query = "DROP TABLE IF EXISTS my_table"
cur.execute(query)
conn.commit()
# print(table_name)
I'm running the query against multiple tables with various query and I want to return the name of the table and the action executed each time. Is there a way to get some kind of meta data from cur.execute or conn.commit on the action running?
In the example above I'd like to print the table name (my_table) and the action (DROP TABLE). however I want this to be dynamic. If I'm creating a table I want to the name of the table newly created and the action (CREATE TABLE).
Thanks.
Quick and Dirty
tables = ['table_1', 'table_2', 'table_3']
action = 'DROP TABLE'
for table in tables:
cur.execute(f'{str(action)} IF EXISTS {str(table)}')
print(f'ACTION: {action}')
print(f'TABLE: {table}')
conn.commit()
HOWEVER, please do not ever do something like this in anything other than a tiny app that will never leave your computer, and especially not with anything that will accept input from a user.
Bad things will happen.
Dynamically interfacing with databases using OOP is a solved problem, and its not worth reinventing the wheel. Have you considered using an ORM like SQLAlchemy?
I am learning pl/sql. I want to ask a question for importing excel files.
I create a table after that import data from excel nearly 100 rows.
I wonder how can i see this query basic like;
insert into table_name (column1,colum2,...,columnn )
values (value1, value2, ... , value n); and other 100 rows..
Sincerely
I'm not sure whether there is a feature within Oracle engine itself, but I can think of two ways to get those queries:
1. Use Oracle SQL Developer (Or another GUI with the same features) :
Oracle SQL Developer (Download link here) is a free tool developed by Oracle to interact with the database. Add the connection for your database and connect to it, then follow these guidelines carefully to generate your insert script.
2. Use v$sql (Experimental) :
Right now I have no access to an Oracle database to check this, but theoretically, if the database is a development/training one, there should not be a lot of activities and queries inside, so you can query the v$sql table to find the last 100 (or whatsoever) queries:
SELECT SQL_FULLTEXT FROM V$SQL WHERE ROWNUM < 1000 ORDER BY FIRST_LOAD_TIME desc;
Check for the ones starting with INSERT INTO {THE_TABLE_WHICH_HAS_IMPORTED_DATA} to find your insert lines.
As I mentioned, this method is quite experimental and might confuse you, so I strongly suggest using Oracle SQL Developer.
Full-Text search in Cassandra;
I am fairly new to Cassandra, and wish to understand it more properly. I am attempting to perform a Full-Text search in Cassandra, but after some research I have found that there may not be a "simple" approach for this.. and I say maybe because the first page of Google hasn't said much of anything.
So I am trying to understand now instead, what is the best approach here.. This sort of lead me to take make up my own assumptions based on what I've learned so far about Cassandra, that is based on these two principals; a) design your tables based on your queries, rather than the data, and b) more-data is a good thing, as long as it is being used properly.
With that being said, I've come up with a couple of solutions I'd like to share, and also ask that if anyone has a better idea, please fill me on it before I commit to anything unreasonable/naive.
First Solution: Create a Column Family(CF), with two primary keys and an Index like so:
CREATE TABLE "FullTextSearch" (
"PartialText" text,
"TargetIdentifier" uuid,
"CompleteText" text,
"Type" int,
PRIMARY KEY ("PartialText","TargetIdentifier")
);
CREATE INDEX IX_FullTextSearch_Type "keyspace"."FullTextSearch" ("Type");
With the above table, I would need to insert rows for the text "Hello World" as follows:
BATCH APPLY;
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("H",000000000-0000-0000-0000-000000000,"Hello World",1);
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("He",000000000-0000-0000-0000-000000000,"Hello World",1);
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("Hel",000000000-0000-0000-0000-000000000,"Hello World",1);
.....
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("Hello Wor",000000000-0000-0000-0000-000000000,"Hello World",1);
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("Hello Worl",000000000-0000-0000-0000-000000000,"Hello World",1);
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("Hello World",000000000-0000-0000-0000-000000000,"Hello World",1);
.....
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("Wor",000000000-0000-0000-0000-000000000,"Hello World",1);
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("Worl",000000000-0000-0000-0000-000000000,"Hello World",1);
INSERT INTO "FullTextSearch" ("PartialText","TargetIdentifier","CompleteText","Type") VALUES ("World",000000000-0000-0000-0000-000000000,"Hello World",1);
END BATCH;
Basically, the above will satisfy the following wildcards/partialtext "%o W%", "Hello%", "Worl%"; However it will not satisfy partial words such as "%ell%" for "Hello", which I can feel alright about for now..... (OCD sorta kicks in here)
This approach sort of sucks for me because I would now have to delete/re-insert any time a save/name change occurs on the "TargetIdentifier";
The Second Solution, would be very similar only this time making use of wide-columns; where the table might look like:
CREATE TABLE "FullTextSearch" (
"TargetIdentifier" uuid,
"Type" int,
"CompleteText" text,
PRIMARY KEY("TargetIdentifier")
);
and now during a search something like:
SELECT * FROM "FullTextSearch" WHERE "He" = 1;
so that if the column exists, the respective rows are returned;
Third Solution:
similar to the one above, only this time instead of using wide-columns we use a set column such as map for the partial texts, and perform a query like:
SELECT * FROM "FullTextSearch" WHERE "PartialTexts"['He'] = 1;
Anyways, I am all out of ideas, it is late, and I can only hope for a great response! Please, let me know what I should be doing here... am I even on the right path?
AFAIK Datastax Enterprise Search is the (commercial) successor of Solandra.
Cassandra 2.0 supports so called "custom secondary indexes".
Custom secondary indexes are Java code. Your own implementation has to implement the abstract class org.apache.cassandra.db.index.SecondaryIndex
(See http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/create_index_r.html)
I'm not sure whether implementations exist for Elasticsearch or Solr.
I would not recommend to code all the weird full text search logic like stemming, multiple/exotic language support or even geo spatial stuff.
But SecondaryIndexwould be a good point to start integrating your favorite search engine.
If your dataset is relative small you can simply use a inmemory instance of lucene, update the index at a set interval and you are ready to go.
Use elassandra which comes elasticsearch as a plugin in cassandra.
An example can be found from here
Check out SOLANDRA (former Lucandra)
But I think Solandra is not being actively developed any more, the author moved to Datastax and continued his work there.
So You can also take a look at Datastax Enterprise Search
There are some limitation also, look at DistributedSearch
The very basic thing about cassandra is if you want to use where clause for filtration of records that column is either primary key or you have to assign index to it, so what i can see is you have given primary key to "TargetIdentifier" field and index to "Type" and using "CompleteText" in where clause so this may not work..
Assign secondary index to "CompleteTex" and check whether you are getting desired output or not.
A couple other options you have:
Stratio Lucene Plugin. This uses Lucene for implementing a native secondary index.
You also have SSTable Attached Secondary Index (SASI) available to use for free text searching.
Be forewarned that both of these strategies use locally distributed indexes such that queries will not be very performant since searches will end up being broadcast across the entire cluster. For SASI, you can avoid this if you can use a partition key as part of your query.
Use Solr for fullText search
Cassandra is not good for fullText.
1 Db Cassandra for Archive
2 Solr for full text search
I have found out that SubSonic SimpleRepository expectes plural table names however I have started working on a database that doesn't have this and I am unable to change the table names.
Is there a way I can use Subsonic without making database changes?
I have seen one suggestion but I don't fancy that too much.
I'm not tied to using the SimpleRepository I just thought it would be easiest as I need the ability to swap database connections (SQL & Oracle) based on the clients requirements. The schema is the same on both. With SimpleRepository I can just swap out the connection string in the web.config.
You can apply the SubSonicTableNameOverride attribute on your classes you use with Simple Repo and use an arbitrary table name!