How to Update the String attributre in RT Index? And also how to declare multi value attibute (MVA)
example like integer/string attribute
rt_attr_uint = field1
rt_attr_string = field2
Right now, there is no UPDATE support for string attributes. You can only replace the whole row.
Declaring a MVA on a RT index is very simple, works just the same as any other attribute, but remember its numeric only.
rt_attr_multi = my_tags
http://sphinxsearch.com/docs/current.html#conf-rt-attr-multi
Related
If I have a string for example:
"this.is.a.string.and.I.need.the.last.part"
I am trying to get the last part of the string after the last ".", which in this case is "part"
How to I achieve this?
One way I tried was to split the string on ".", I get a array back, but then I don't know how to retrieve the last item in the array.
| extend ToSplitstring = split("this.is.a.string.and.I.need.the.last.part", ".")
gives me:
["this", "is","a","string","and","I","need","the","last", "part"]
and a second try I have tried this:
| extend ToSubstring = substring(myString, lastindexof(myString, ".")+1)
but Kusto do not have a function of lastindexof.
Anyone with tips?
you can access the last member of the array using a negative index -1.
e.g. this:
print split("this.is.a.string.and.I.need.the.last.part", ".")[-1]
returns a single table, with a single column and a single record, with the value part
You can try the code below, and feel free to change it to meet your need:
let lastIndexof = (input:string, lookup: string) {
indexof(input, lookup, 0, -1, countof(input,lookup))
};
your_table_name
| extend ToSubstring = substring("this.is.a.string.and.I.need.the.last.part", lastIndexof("this.is.a.string.and.I.need.the.last.part", ".")+1)
To query empty fields I have seen this answer:
Postgresql, select empty fields
(unfortunately I don't have enough reputation points to answer #wildplasser on that post, so here we go)
Wildplasser's answer:
SELECT mystr, mystr1
FROM mytable
WHERE COALESCE(mystr, '') = ''
OR COALESCE(mystr1, '') = ''
;
I am not sure I get the COALESCE method, but it also works for me this way (specific for my string data type):
SELECT mystr, mystr1
FROM mytable
WHERE mystr = '' ;
My questions are:
Does COALESCE work for any data type?
Is there any better way to query empty strings? i.e., column_value = ' '
First you need to understand the difference between NULL and "empty".
NULL is the absence of a value. Any (or at least almost any) data type can be NULL. When you have a column of type integer, and you don't want to put a value in that field, you put NULL.
"Empty" is a string/text concept. It's a string with an empty value, i.e. ''. A text field with an empty string contains a value: the empty string. It is not the same as containing NULL, i.e. no value. Other data types e.g. integer, boolean, json, whatever, can't have an empty string.
Now to COALESCE. That function works on any data type, and basically it returns the first not-NULL result of its arguments. So COALESCE(NULL, TRUE) returns TRUE because the first argument is NULL; COALESCE(FALSE, TRUE) returns FALSE because the first argument is not NULL; and COALESCE(NULL, NULL) returns NULL because there are no not-NULL arguments.
So, COALESCE(field, '') returns the value of field if it's not NULL, and otherwise returns an empty string. When used in COALESCE(field, '') = '' when trying to find any rows where field is "empty", this is basically saying "if field is NULL then use an empty string in its place, then see if it equals an empty string". This is because NULL and an empty string are not equivalent, and "you" are trying to find any rows where fields are NULL or empty.
In your version of the query, where you just do field = '', that will ONLY return results where field is actually an empty string, not where field is NULL. Which behaviour you desire is up to you.
With COALESCE you will get NULL values too in the first query.
1- In Postgresql, you can't mix datatype example here, but you can use the function to_char to mix values
2- I don't understand your question
I think based on the definition of coalesce itself as
"The COALESCE() function returns the first non-null value in a list."
means that it work for any data type
I don't really understand the question but i think yes its already the most efficient way to make empty string
Do we have any methods in mel to check string contained in some another String or not.
For Example:
I had String like "mel".
I had Another String like "melcode".
Do we have any idea how to check the String "mel" is available in String "melcode".
num indexOf(str inputString1, str inputString2)
if the return value is -1 then inputString1 does not contain inputString2
As mentioned in Is there any possible way to filter movelets using mel from another movlet?
Hi Jaya Sankar, you can use indexOf which returns -1 if the first input String does not contain the second input String. There are also startsWith and endsWith as methods.
I am currently working on a project that dynamically displays DB content into table.
To edit the table contents i am want to use the dynamically created "string"+id value.
Is there any way to retrieve the appended int value from the whole string in javaScript?
Any suggestions would be appreciative...
Thanks!!!
If you know that the string part is only going to consist of letters or non-numeric characters, you could use a regular expression:
var str = "something123"
var id = str.replace(/^[^\d]+/i, "");
If it can consist of numbers as well, then things get complicated unless you can ensure that string always ends with a non-numeric character. In which case, you can do something like this:
var str = "something123"
var id = str.match(/\d+$/) ? str.match(/\d+$/)[0] : "";
(''+string.match(/\d+/) || '')
Explanation: match all digits in the variable string, and make a string from it (''+).
If there is no match, it would return null, but thanks to || '', it will always be a string.
You might try using the regex:
/\d+$/
to retrieve the appended number
If I have a struct with a fieldname 'fieldname', is it possible to access the data in that field using only the variable?
ie.
x = 'fieldname'
is it possible to do
data = struct.(x) in some way? I want to use the string in x as the field name.
Yes, this is possible using the TAG_NAMES function:
tnames=TAG_NAMES(struct)
tindex=WHERE(STRCMP(tnames,'fieldname') EQ 1)
data=struct.(tindex)
The call to TAG_NAMES returns an array of strings representing the tags defined in struct.
The WHERE statement returns the index in tnames of a string matching 'fieldname'.
Finally, the index is passed to the struct.(tindex) operation, which extracts a field by
its numeric tag index.
Of course, in a real application you'd want to check whether tindex was successfully
matched to something, otherwise IDL will choke on the structure lookup with an index
of -1.