matchPrefix
Syntax
matchPrefix(textCol, prefix)
Arguments
textCol is the column to be searched, i.e., the column with text indexing set in the PKEY engine.
prefix is a STRING scalar specifying the prefix to search for.
Details
Perform prefix-based text searches on the column with text indexing set in the PKEY
engine. This function is used in the where
clause of a SQL
statement.
Return value: Rows containing words with the specified prefix.
Examples
// Generate data for queries
stringColumn = ["There are some apples and oranges.","Mike likes apples.","Alice likes oranges.","Mike gives Alice an apple.","Alice gives Mike an orange.","John likes peaches, so he does not give them to anyone.","Mike, can you give me some apples?","Alice, can you give me some oranges?","Mike traded an orange for an apple with Alice."]
t = table([1,1,1,2,2,2,3,3,3] as id1, [1,2,3,1,2,3,1,2,3] as id2, stringColumn as remark)
if(existsDatabase("dfs://textDB")) dropDatabase("dfs://textDB")
db = database(directory="dfs://textDB", partitionType=VALUE, partitionScheme=[1,2,3], engine="PKEY")
pt = createPartitionedTable(dbHandle=db, table=t, tableName="pt", partitionColumns="id1",primaryKey=`id1`id2,indexes={"remark":"textindex(parser=english, lowercase=true, stem=true)"})
pt.tableInsert(t)
// Search for rows containing words prefixed with "app"
select * from pt where matchPrefix(remark,"app")
id1 | id2 | remark |
---|---|---|
1 | 1 | There are some apples and oranges. |
1 | 2 | Mike likes apples. |
2 | 1 | Mike gives Alice an apple. |
3 | 1 | Mike, can you give me some apples? |
3 | 3 | Mike traded an orange for an apple with Alice. |