fulltext index (CONTAINS) does not return all results

Question

Among more than 100 million text (abstracts of publications) indexed in my db (microsoft sql) table, I want to fetch all those abstracts containing the phrase 'machine learning'. To do so, I have created the full text as below:

CREATE FULLTEXT CATALOG ftCatalogForAbstract AS DEFAULT;

CREATE UNIQUE NONCLUSTERED INDEX IX_ABSTRACT 
ON ABSTRACT_table (ID)

CREATE FULLTEXT INDEX ON ABSTRACT_table
(
    ABSTRACT                      --Full-text index column name 
    Language 2057                 --2057 is the LCID for British English
)
KEY INDEX IX_ABSTRACT ON ftCatalogForAbstract
WITH CHANGE_TRACKING AUTO

now I can query:

SELECT * FROM ABSTRACT_table
WHERE CONTAINS(ABSTRACT, '"machine learning"')

Whenever I run the query, I always get a different result set (sometimes 19K rows, sometimes 43K rows...). So is there a way to get all the results in a stable way?

Answer 1

I never had this case of raying result. The only thing I can image is, that there are large updates on the base table; a full-text index get updates asynchron in background, so that it can take some time until new/change data appears in a search result.