I will be dynamically combining a range of tables with the exact same structure in RethinkDB.
I have my dynamically-generated list of tables in an array as follows:
tables = [r.table('table1'), r.table('table2'), ...]
And I am trying to do this:
r.union(r.args(tables))
But that just gives me an error: ReqlLogicError: Expected type DATUM but found TABLE
Overall, I have not been able to find a way to generate a list of tables in JavaScript and to add use r.union to combine them into a stream. Would appreciate help on this.
Thanks!
You can use reduce to do what you want, we merge one by one, like r.table(t1).union(r.table(t2)).union(r.table(t3)).
Like this:
[r.table('t1'), r.table('t2'), r.table('t3')].reduce(function(p, c) {
return p.union(c)
})
Try it from data explorer.
The answer provided by kureikain works. I still wish the functionality existed in RethinkDB with r.args() (it seems to me that this would be consistent with the documentation of that function).
Moreover, one important tip tangentially related to this question: if you want to combine multiple tables into a stream through r.union() but be able to tell which table it is in the results, use merge(). So my query would look something like this:
[r.db('database').table('table1').merge({source: 'table1'}), r.db('database').table('table2').merge({source: 'table2'})].reduce(function(p, c) { return p.union(c) }).filter( ...)
This allows you to not only combine multiple tables into one stream, but to always distinguish between the source tables in your results (by looking up the value of the key 'source').
Related
I have a PowerApps gallery that lists data from 3 different tables and have it normally sorted by the following:
SortByColumns(Filter(Personnel, !Dismissed, txtMSSearchBox.Text in MemberName), "MemberName", If(SortDescending1, SortOrder.Descending, SortOrder.Ascending))
One of the fields is displayed from the below:
Last(SortByColumns(Filter(PersonnelEvents, MemberNumber.Id = ThisItem.ID, EventType.Value="Promotion"), "Date", SortOrder.Ascending)).Title
What I would like to do is sort the gallery by this derived data. Is this even possible?
Can you try making On visible of the screen have an UpdateContext function which saves this formula as a variable.
You can then reference this variable as the column you want to sort by.
i.e something like UpdateContext({mySortColumn: Last(SortByColumns(Filter(PersonnelEvents, MemberNumber.Id = ThisItem.ID, EventType.Value="Promotion"), "Date", SortOrder.Ascending)).Title})
I just hope I really understand what you are trying to achieve, but if this doesn't work, maybe you can explain better what you are trying to do and hopefully I'll be able to help
I have decided to use Flow to update a column in my main table to show the relevant data and thereby sort by that field. I believe this would be an easier way to accomplish what I want.
I want to get a list of all distinct document structures with a count in a Marklogic database.
e.g. a database with these 3 documents:
1) <document><name>Robert</name></document>
2) <document><name>Mark</name></document>
3) <document><fname>Robert</fname><lname>Smith</lname></document>
Would return that there are two unique document structures in the database, one used by 2 documents, and the other used by 1 document.
I am using this xquery and am getting back the list of unique sequence of elements correctly:
for $i in distinct-values(for $document in doc()
return <div>{distinct-values(
for $element in $document//*/*/name() return <div>{$element}</div>)} </div>)
return $i
I appreciate that this code will not handle duplicate element names but that is OK for now.
My t questions are:
1) Is there a better/more efficient way to do this? I am assuming yes.
2) Is there a way to get back enough detail so that I could build up the xml tree of each unique structure?
3) What is the best way to return the count of each distinct structure e.g. 2 and 1 and in the above example
If you have a finite list of elements for which you need to do this for, consider co-occurance or other similiar solutions: https://docs.marklogic.com/cts:value-co-occurrences
This requires a range index on each element in question.
MarkLogic works best to use indexes whenever possible. The other solution I can think of is that you actually create a hash/checksum for the values of the target content for each document in question and store this with the document (or in a triple if you happen to have a licence for semantics). Then you you would already have a key for
the unique combinations.
1) Is there a better/more efficient way to do this? I am assuming yes.
If it were up to me, I would create the document structured in a consistent fashion (like you're doing), then hash it, and attach the hash to each document as a collection. Then I could count the docs in each collection. I can't see any efficient way (using indexes) to get the counts without first writing to the document content or metadata (collection is a type of metadata) then querying against the indexes.
2) Is there a way to get back enough detail so that I could build up the xml tree of each unique structure?
After you get the counts for each collection, you could retrieve one doc from each collection and walk through it to build an empty XML structure. XSLT would probably be a good way to do this if you already know XSLT.
3) What is the best way to return the count of each distinct structure e.g. 2 and 1 and in the above example
Turn on the collection lexicon on your database. Then do something like the following:
for $collection in cts:collections()
return ($collection, cts:frequency($collection))
Not sure I follow exactly what you are after, but I am wondering if this is more what you are looking for- functx:distinct-element-paths($doc)
http://www.xqueryfunctions.com/xq/functx_distinct-element-paths.html
Here's a quick example:
xquery version "1.0-ml";
import module namespace functx = "http://www.functx.com" at "/MarkLogic/functx/functx-1.0-nodoc-2007-01.xqy";
let $doc := <document><fname>Robert</fname><lname>Smith</lname></document>
return
functx:distinct-element-paths($doc)
Outputs the following strings (which could be parsed, of course):
document
document/fname
document/lname
there are existing 3rd party tools that may work, depending on the size of the data, and the coverage required (is 100% sampleing needed).
Search for "Generate Schema from XML" --
Such tools will look at a sample set and infer a schema (xsd, dtd, rng etc).
They do an accurate job, but not always in the same way a human would.
If they do not have native ML integration then you need to expose a service or exort the data for analysis.
Once you HAVE a schema, load it into MarkLogic, and you can query the schema (and elements validated by it) directly and programmatically in ML
If you find a 'generate schema' tool that is implemented in XSLT, XQuery, or JavaScript you may be able to import and execute it in-server.
Following is the data model of the dashboard I am facing problem in:
http://blob:http://stackoverflow.com/f3e40cfe-e009-4d03-bcf5-b7b4305c18c4
Now, what i want to achieve is that in Case there is a filed named Manufacturing_Date. And in MWODefetcs there is a field named Defect_Date. What i want is that when ever a record is selected from a table containing cases from Case corresponding records are shown in another table based on the exact match of Manufacturing_Date=Defect_Date.
As simple as it sounds, i can not seem to accomplish it. I have tried the following expressions to no avail:
Count({<[Defect_Date_text]=p([Manu_text]),FaultID=,DEFECT_CODE=>}MFG_BARCODE_NUM)
sum({$<Defect_Date ={"=$(Manufacturing_Date__c)"}>}Defect_Date)
Do the 2 tables need to be directly linked. Is it the intermediary iFaults table that is preventing me to accomplish it?
Please help.
you should use the P() set expression like this:
sum({$<Defect_Date =P(Manufacturing_Date__c) >}Defect_Date)
Say i have something like this:
somerecord SOMETABLE%ROWTYPE;
Is it possible to access the fields of somerecord with out knowing the fields names?
Something like somerecord[i] such that the order of fields would be the same as the column order in the table?
I have seen a few examples using dynamic sql but i was wondering if there is a cleaner way of doing this.
What i am trying to do is generate/get the DML (insert query) for a specific row in my table but i havent been able to find anything on this.
If there is another way of doing this i'd be happy to use but would also be very curious in knowing how to do the former part of this question - it's more versatile.
Thanks
This doesn't exactly answer the question you asked, but might get you the result you want...
You can query the USER_TAB_COLUMNS view (or the other similar *_TAB_COLUMN views) to get information like the column name (COLUMN_NAME), position (COLUMN_ID), and data type (DATA_TYPE) on the columns in a table (or a view) that you might use to generate DML.
You would still need to use dynamic SQL to execute the generated DML (or at least generate static SQL separately).
However, this approach won't work for identifying the columns in an arbitrary query (unless you create a view of it). If you need that, you might need to resort to DBMS_SQL (or other tools).
Hope this helps.
As far as I know there is no clean way of referencing record fields by their index.
However, if you have a lot of different kinds of updates of the same table each with its own column set to update, you might want to avoid dynamic sql and look in the direction of statically populating your record with values, and then issuing update someTable set row = someTableRecord where someTable.id = someTableRecord.id;.
This approach has it's own drawbacks, like, issuing an update to every, even unchanged column, and thus creating additional redo log data, but I believe it should be considered.
I've got a file filled with records like this:
NCNSCF1124557200811UPPY19871230
The codes are all fixed-length, and some of them link to other flat files (sort of like a relational database). What's the best way of querying this data using LINQ?
This is what I came up with intuitively, but I was wondering if there's a more elegant way:
var records = File.ReadAllLines("data.txt");
var table = from record in records
select new { FirstCode = record.Substring(0, 2),
OtherCode = record.Substring(18, 4) };
For one thing I wouldn't read it all into memory to start with. It's very easy to write a LineReader class which iterates over a file a line at a time. I've got a version in MiscUtil which you can use.
Unless you only want to read the results once, however, you might want to call ToList() at the end to avoid reading the file multiple times. (This is still nicer than reading all the lines and keeping that in memory - you only want to do the splitting once.)
Once you've basically got in-memory collections of all the tables, you can use normal LINQ to Objects to join them together etc. You might want to go to a more sophisticated data model to get indexes though.
I don't think there's a better way out of the box.
One could define a Flat-File Linq Provider which could make the whole thing much simpler, but as far as I know, no one has yet.