I am trying to update new password after reset to cassandra db. This is the query I have written where both username and password fields are dynamic. Is this right?
def update_db(uname, pwd):
query = session.prepare('update user.userdetails set "password"=%s where "username" = ? ALLOW FILTERING', pwd)
session.execute(query, (uname,))
update_db(username, new_pwd)
I am calling this through an API. But it doesn't seem to update.
Alex is absolutely correct in that you need to provide the complete PRIMARY KEY for any write operation. Remove ALLOW FILTERING and your query should work as long as your primary key definition is: PRIMARY KEY (username).
Additionally, it's best practice to parameterize your entire prepared statement, instead of relying on string formatting for password.
query = session.prepare('update user.userdetails set "password"=? where "username"=?')
session.execute(query,[pwd,uname])
Note: If at any point you find yourself needing the ALLOW FILTERING directive, you're doing it wrong.
for updating record you need to provide primary key(s) completely. It will not work with ALLOW FILTERING - you need first to get all primary keys that you want to update, and then issue individual update commands. See the documentation for more detailed description of UPDATE command.
If you really want to specify the default value for some column - why not simply handle it with something like .get('column', 'default-value')?
Related
This question is a bit related to another question: Get List of Primary Key Columns in Snowflake.
Since INFORMATION_SCHEMA.COLUMNS does not provide the required information regarding the primary keys. And the method proposed by Snowflake itself, where you would describe the table followed by a result_scan, is unreliable when queries are run in parallel.
I was thinking about using SHOW PRIMARY KEYs IN DATABASE. This works great when querying the database from within Snowflake. But as soon as I try to do this in python, I get results for the column name like 'Built-in function id'. Which is not useful when dynamically generating sql statements.
The code I am using is as follows:
SQL_PK = "SHOW PRIMARY KEYS IN DATABASE;"
snowflake_service = SnowflakeService(username=cred["username"], password=cred["password"])
snowflake_service.connect(database=DATABASE,role=ROLE, warehouse=WAREHOUSE)
curs = snowflake_service.cursor
primary_keys = curs.execute(SQL_PK).fetchall()
curs.close()
snowflake_service.connection.close()
Is there something I am doing wrong? Is it even possible to do it like this?
Or is the solution that Snowflake provides reliable enough, when sending these queries as one string? Although with many tables, there will be many round trips required to get all the data needed.
where you would describe the table followed by a result_scan, is unreliable when queries are run in parallel
You could search for specific query run using information_schema.query_history_by_session and then refer to resultset using retrieved QUERY_ID.
SHOW PRIMARY KEYS IN DATABASE;
-- find the newest occurence of `SHOW PRIMARY KEYS`:
SET queryId = (SELECT QUERY_ID
FROM TABLE(information_schema.query_history_by_session())
WHERE QUERY_TEXT LIKE '%SHOW PRIMARY KEYS IN DATABASE%'
ORDER BY ENDTIME DESC LIMIT 1);
SELECT * FROM TABLE(RESULT_SCAN($queryId));
I would like to search my database for a value. I know you can do this for a key with db.search() but there does not seem to be any kind of similar function for searching for a value
I've tried using the contains() function but I have the same issue. It checks if the key is contained in the database. I would like to know if a certain value is contained in the database.
I would like to do something like this that would search for values in tinydb
db.search('value')
If I was able to execute the above command and get the value(if it does exist) or Nothing if it doesn't that would be ideal. Alternatively, if the able returned True or False accordingly, that would be fine as well
I don't know if this is what you are looking for but which the following command you can check for a specific field value:
from tinydb import Query
User = Query()
db.search(User.field_name == 'value')
I'm new here (doing some reading to see if TinyDB would even be applicable for my use case) so perhaps wrong, and also aware that this question is a little old. But I wonder if you can't address this by iterating over each field and searching within for your value. Then, you couldget the key or field wherein a value match was located.
I'm trying to use https://pandas.pydata.org/pandas-docs/version/0.21/generated/pandas.DataFrame.to_sql.html
When I change the Name argument, e.g. say I set
pd.to_sql(name="testTable",constring)
the actual table name comes up as [UserName].[testTable] rather than just [testTable]
Is there a way I can get rid of the [userName]? which is linked to the user who runs the script?
The [UserName] portion of the table name is the schema that the table is in. I don't know which database engine you're using, but the schema you're looking for might be "dbo".
According to the documentation, you can provide a schema argument:
pd.to_sql(name="testTable",constring, schema="dbo")
Note that if the schema is left blank, it uses the DB user's default schema (as defined when the user was added to the database), which in your case, appears to be the schema of the user.
I have a Postgres 9.3 table that has a column called id as PKEY, id is char(9), and only allow lowercase a-z0-9, I use Python with psycopg to insert to this table.
When I need to insert into this table, I call a Python function get_new_id(), my question is, how to make get_new_id() efficient?
I have the following solutions, none of them satisfy me.
a) Pre-generate a lot of ids, store them in some table, when I need a new id, I SELECT one from this table, then delete it from this table, then return this selected id. Down side of this solution is that it need to maintain this table, in each get_new_id() call, there will also have a SELECT COUNT in order to find out if I need to generate more ids to put into this table.
b) When get_new_id() gets called, it generate a random id, then pass this id to a stored procedure to check if this id is already in use, if no, we are good, if yes, do b) again. Down side of this solution is, when the table gets bigger, the failure rate may be high, and there is a chance that, two get_new_id() calls in two processes will generate the same id, say, 1234567, and 1234567 is not used a PKEY yet, so, when insert, one process will fail.
I think this is a pretty old problem, what's the perfect solution?
Edit
I think this has been answered, see Jon Clements' comment.
Offtopic because you already have a char(9) datatype:
I would use an UUID when a random string is needed, it's a standard and almost any programming language (including Python) can generate UUIDs for you.
PostgreSQL can also do it for you, using the uuid-ossp extension.
select left(md5(random()::text || now()), 9);
left
-----------
c4c384561
Make the id the primary key and try the insert. If an exception is thrown catch it and retry. Nothing fancy about it. why only 9 characters? Make it the full 32.
Check this answer for how to make it smaller: https://stackoverflow.com/a/15982876/131874
Help! Can't figure this out! I'm getting a Integrity error on get_or_create even with a defaults parameter set.
Here's how the model looks stripped down.
class Example(models.Model):model
user = models.ForeignKey(User)
text = models.TextField()
def __unicode__(self):
return "Example"
I run this in Django:
def create_example_model(user, textJson):
defaults = {text: textJson.get("text", "undefined")}
model, created = models.Example.objects.get_or_create(
user=user,
id=textJson.get("id", None),
defaults=defaults)
if not created:
model.text = textJson.get("text", "undefined")
model.save()
return model
I'm getting an error on the get_or_create line:
IntegrityError: (1062, "Duplicate entry '3020' for key 'PRIMARY'")
It's live so I can't really tell what the input is.
Help? There's actually a defaults set, so it's not like, this problem where they do not have a defaults. Plus it doesn't have together-unique. Django : get_or_create Raises duplicate entry with together_unique
I'm using python 2.6, and mysql.
You shouldn't be setting the id for objects in general, you have to be careful when doing that.
Have you checked to see the value for 'id' that you are putting into the database?
If that doesn't fix your issue then it may be a database issue, for PostgreSQL there is a special sequence used to increment the ID's and sometimes this does not get incremented. Something like the following:
SELECT setval('tablename_id_seq', (SELECT MAX(id) + 1 FROM
tablename_id_seq));
get_or_create() will try to create a new object if it can't find one that is an exact match to the arguments you pass in.
So is what I'm assuming is happening is that a different user has made an object with the id of 3020. Since there is no object with the user/id combo you're requesting, it tries to make a new object with that combo, but fails because a different user has already created an item with the id of 3020.
Hopefully that makes sense. See what the following returns. Might give a little insight as to what has gone on.
models.Example.objects.get(id=3020)
You might need to make 3020 a string in the lookup. I'm assuming a string is coming back from your textJson.get() method.
One common but little documented cause for get_or_create() fails is corrupted database indexes.
Django depends on the assumption that there is only one record for given identifier, and this is in turn enforced using UNIQUE index on this particular field in the database. But indexes are constantly being rewritten and they may get corrupted e.g. when the database crashes unexpectedly. In such case the index may no longer return information about an existing record, another record with the same field is added, and as result you'll be hitting the IntegrityError each time you try to get or create this particular record.
The solution is, at least in PostgreSQL, to REINDEX this particular index, but you first need to get rid of the duplicate rows programmatically.