I've got a bit of a semantic question about Orient SQL queries.
Take for example this very simple graph:
v(#12:1 User) --> e(#13:1 FriendOf) --> v(#12:2 User)
In other words, a given User with an rid of #12:1 is friends with another user with an rid of #12:2.
To get the friends of user #12:1, one might express this in Orient SQL like so:
SELECT EXPAND(both("FriendOf")) FROM #12:1
This query would return a result list comprised of the User with rid #12:2.
Now lets say I want to filter that result list by an additional criteria, like say a numeric value ("age"):
SELECT EXPAND(both("FriendOf")) FROM #12:1 WHERE age >= 10
The above query would filter the CURRENT vertex (#12:1), NOT the result set. Which makes sense, but is there a way to apply the filter to the EXPAND(both("FriendOf")) result rather than the current vertex? I know I can do this with gremlin like so:
SELECT EXPAND(gremlin('current.both("FriendOf").has("age",T.gte,10)')) FROM #12:1
But the above does not seem to make use of indexes (at least not when I ask it to explain). For very large data sets, this is problematic.
So is there a proper way to apply a WHERE statement to the resulting data set?
Thanks !
... is there a way to apply the filter to the EXPAND(both("FriendOf")) result rather than the current vertex?
The simple answer is to embed your basic "SELECT EXPAND ..." within another SELECT, i.e.
SELECT FROM (SELECT EXPAND(both("FriendOf")) FROM #12:1) WHERE age >= 10
By the way, on my Mac, the above took .005s compared to over 2s for the Gremlin version. There must be a moral there somewhere :-)
Related
I have a list of chemicals in my database and I provide our users with the ability to do a live search via our website. I use SQLAlchemy and the query I use looks something like this:
Compound.query.filter(Compound.name.ilike(f'%{name}%')).limit(50).all()
When someone searches for toluene, for example, they don't get the result they're looking for because there are many chemicals that have the word toluene in them, such as:
2, 4 Dinitrotoluene
2-Chloroethyl-p-toluenesulfonate
4-Bromotoluene
6-Amino-m-toluenesulfonic acid
a,2,4-trichlorotoluene
a,o-Dichlorotoluene
a-Bromtoluene
etc...
I realize I could increase my limit but I feel like 50 is more than enough. Or, I could change the ilike(f'%{name}%')) to something like ilike(f'{name}%')) but our business requirements don't want this. What I'd rather do is improve the ability for Postgres to return results so that toluene is at the top of the search results.
Any ideas on how Postgres' ilike capability?
Thanks in advance.
One option is to better rank the results. Postgres text search allows you to rank the results.
A cheap and dirty version of preferential ranking is to do multiple queries for name = ?, ilike(f'{name}%')), and ilike(f'%{name}%')) using a union. That way the ilike(f'{name}%')) results come first.
And rather than a hard limit, offer pagination. SQLAlchemy has paginate to help.
ILIKE yields a boolean. It doesn't specify what order to return the results, just whether to return them at all (you can order by a boolean, but if you only return trues there is nothing left to order by). So by the time you are done improving it, it would no longer be ILIKE at all but something else completely.
You might be looking for something like <-> from pg_trgm, which provides a distance score which can be sorted on. Although really, you could just order the result based on the length of the compound name, and return the shortest 50 that contain the target.
something like ilike(f'{name}%')) but our business requirements don't want this
Isn't your business requirement to get better results?
But at least in my database, this could just return a bunch of names in inverted format, like toluene, 2,4-dinitro, so the results might not be much better, unless you avoid storing such inverted names. Sorting by either <-> or by length would overcome that problem. But they would also penalize toluene, ACS reagent grade 99.99% by HPLC, should you have names like that.
I have a query like this, which we use to generate data for our custom dashboard (A Rails app) -
SELECT AVG(wait_time) FROM (
SELECT TIMESTAMPDIFF(MINUTE,a.finished_time,b.start_time) wait_time
FROM (
SELECT max(start_time + INTERVAL avg_time_spent SECOND) finished_time, branch
FROM mytable
WHERE name IN ('test_name')
AND status = 'SUCCESS'
GROUP by branch) a
INNER JOIN
(
SELECT MIN(start_time) start_time, branch
FROM mytable
WHERE name IN ('test_name_specific')
GROUP by branch) b
ON a.branch = b.branch
HAVING avg_time_spent between 0 and 1000)t
GROUP BY week
Now I am trying to port this to tableau, and I am not being able to find a way to represent this data in tableau. I am stuck at how to represent the inner group by in a calculated field. I can also try to just use a custom sql data source, but I am already using another data source.
columns in mytable -
start_time
avg_time_spent
name
branch
status
I think this could be achieved new Level Of Details formulas, but unfortunately I am stuck at version 8.3
Save custom SQL for rare cases. This doesn't look like a rare case. Let Tableau generate the SQL for you.
If you simply connect to your table, then you can usually write calculated fields to get the information you want. I'm not exactly sure why you have test_name in one part of your query but test_name_specific in another, so ignoring that, here is a simplified example to a similar query.
If you define a calculated field called worst_case_test_time
datediff(min(start_time), dateadd('second', max(start_time), avg_time_spent)), which seems close to what your original query says.
It would help if you explained what exactly you are trying to compute. It appears to be some sort of worst case bound for avg test time. There may be an even simpler formula, but its hard to know without a little context.
You could filter on status = "Success" and avg_time_spent < 1000, and place branch and WEEK(start_time) on say the row and column shelves.
P.S. Your query seems a little off. Don't you need an aggregation function like MAX or AVG after the HAVING keyword?
I am getting my data from denormalized table, where I keep names and actions (apart from other things). I want to create a calculated field that will return sum of workgroup names but only when there are more than five actions present in DB for given workgroup.
Here's how I have done it when I wanted to check if certain action has been registered for workgroup:
WINDOW_SUM(COUNTD(IF [action] = "ADD" THEN [workgroup_name] END))
When I try to do similar thing with count, I am getting "Cannot mix aggregate and non-aggregate arguments":
WINDOW_SUM(COUNTD(IF COUNT([Number of Records]) > 5 THEN [workgroup_name] END))
I know that there's problem with the IF clause, but don't know how to fix it.
How to change the IF to be valid? Maybe there's an easier way to do it, that I am missing?
EDIT:
(after Inox's response)
I know that my problem is mixing aggregate with non-aggregate fields. I can't use filter to do it, because I want to use it later as a part of more complicated view - filtering would destroy the whole idea.
No, the problem is to mix aggregated arguments (e.g., sum, count) with non aggregate ones (e.g., any field directly). And that's what you're doing mixing COUNT([Number of Records]) with [workgroup_name]
If your goal is to know how many workgroup_name (unique) has more than 5 records (seems like that by the idea of your code), I think it's easier to filter then count.
So first you drag workgroup_name to Filter, go to tab conditions, select By field, Number of Records, Count, >, 5
This way you'll filter only the workgroup_name that has more than 5 records.
Now you can go with a simple COUNTD(workgroup_name)
EDIT: After clarification
Okay, than you need to add a marker that is fixed in your database. So table calculations won't help you.
By definition table calculation depends on the fields that are on the worksheet (and how you decide to use those fields to partition or address), and it's only calculated AFTER being called in a sheet. That way, each time you call the function it will recalculate, and for some analysis you may want to do, the fields you need to make the table calculation correct won't be there.
Same thing applies to aggregations (counts, sums,...), the aggregation depends, well, on the level of aggregation you have.
In this case it's better that you manipulate your data prior to connecting it to Tableau. I don't see a direct way (a single calculated field that would solve your problem). What can be done is to generate a db from Tableau (with the aggregation of number of records for each workgroup_name) then export it to csv or mdb and then reconnect it to Tableau. But if you can manipulate your database outside Tableau, it's usually a better solution
I have a UDF in my database which basically tries to get a station (e.g. bus/train) based on some input data (geographic/name/type). Inside this function i try to check if there are any rows matching the given values:
SELECT
COUNT(s.id)
INTO
firsttry
FROM
geographic.stations AS s
WHERE
ST_DWithin(s.the_geom,plocation,0.0017)
AND
s.name <-> pname < 0.8
AND
s.type ~ stype;
The firsttry variable now contains the value 1. If i use the following (slightly extended) SELECT statement i get no results:
RETURN query SELECT
s.id, s.name, s.type, s.the_geom,
similarity(
regexp_replace(s.name::text,'(Hauptbahnhof|Hbf)','Hbf'),
regexp_replace(pname::text,'(Hauptbahnhof|Hbf)','Hbf')
)::double precision AS sml,
st_distance(s.the_geom,plocation) As dist from geographic.stations AS s
WHERE ST_DWithin(s.the_geom,plocation,0.0017) and s.name <-> pname < 0.8
AND s.type ~ stype
ORDER BY dist asc,sml desc LIMIT 1;
the parameters are as follows:
stype = '^railway'
pname = 'Amsterdam Science Park'
plocation = ST_GeomFromEWKT('SRID=4326;POINT(4.9492530 52.3531670)')
the tuple i need to be returned is:
id name type geom (displayed as ST_AsText)
909658;"Amsterdam Sciencepark";"railway_station";"POINT(4.9482893 52.352904)"
The same UDF returns quite well for a lot of other stations, but this is one (of more) which just won't work. Any suggestions?
P.S. The use of the <-> operator is coming from the pg_trgm module.
Some ideas on how to troubleshoot this:
Break your troubleshooting into steps. Start with the simplest query possible. No aggregates, just joins and no filters. Then add filters. Then add order by, then add aggregates. Look at exactly where the change occurs.
Try reindexing the database.
One possibility that occurs to me based on this is that it could be a corrupted index used in the second query but not the first. I have seen corrupted indexes in the past and usually they throw errors but at least in theory they should be able to create a problem like this.
If this is correct, your query will suddenly return rows if you remove the ORDER BY clause.
If you have a corrupted index, then you need to pay close attention to hardware. Is the RAM ECC? Is the processor overheating? How are you disks doing?
A second possibility is that there is a typo on a join condition of filter statement. Normally this is something I would suspect first but it is easy enough to weed out index problems to start there. If removing the ORDER BY doesn't change things, then chances are it is a typo. If you can't find a typo, then try reindexing.
I have a database of filenames in which I'm trying to search using PGs full text search facility. I'm running the search query on a table of filenames, the problem is that the ranking functions are not ranking the results as I'd like them to do. For the sake of argument, let's assume the schema looks like this:
create table files (
id serial primary key,
filename text,
filename_ft tsvector
);
The query that I run looks something like this:
select filename, ts_rank(filename_ft, query)
from files, to_tsquery('simple', 'a|b|c') as query
where query ## name_ft
order by rank desc limit 5;
This will return the 5 results with the highest rank. However, those search queries are coming from another process, and in most cases the queries have some 'garbage' in them. For instance, a query for 'a xxxx' might be executed, where xxxxx is just a bunch of other terms. In most cases this still returns the correct results, because the suffix is simply not in the database.
However, sometimes a query contains some extraneous information that screws with the ranking function. For instance, a query for 'a b c' will return a filename containing the tokens 'b c' as first result, and an exact match on 'a' as second result, my guess this is due to the fact the the first result contains a larger percentage of the actual search tokens.
In most cases (if not all) the most important token appears as the first token in the query, so my question is, is there a way to give the tokens in the query a weight?
is there a way to give the tokens in the query a weight?
Yes, there is. See the documentation; search for "weight".
Whether assigning weights is the right choice is another matter. It sounds to me like you really want to exclude some of the data from the inputs to to_tsvector in index creation and searching, so you just don't include that garbage in the index.