Filter
There are many types of filters, but they can be divided into two categories - Comparative filters and special filters.
The function of the filter is to judge whether the data satisfy the condition at the server side, and then return the data satisfying the condition to the client side only.
The basic API s of HBase include addition, deletion, modification, check and so on.
Addition and deletion are relatively simple operations. Compared with traditional RDBMS, the query operations here are slightly pale, and can only be queried according to the characteristics of the row keys (Get) or according to the range of the row keys (Scan).
HBase not only provides these simple queries, but also provides more advanced filters to query.
Abstract operator (comparison operator)
LESS <
LESS_OR_EQUAL <=
EQUAL =
NOT_EQUAL <>
GREATER_OR_EQUAL >=
GREATER >
NO_OP Exclude all
Comparator (specifying a comparison mechanism)
BinaryComparator compares specified byte arrays in byte index order, using Bytes.compareTo(byte [])
The BinaryPrefixComparator is the same as the previous one, except that the data on the left side is the same.
Null Comparator judges whether a given is empty
Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator Bit Comparator
RegexString Comparator provides a regular comparator that supports only EQUAL and non-EQUAL
Substring Comparator determines whether the supplied substring appears in value
Comparing filters
1. RowFilter (line key filter or rowkey filter)
Filter rowFilter = new RowFilter(CompareOp.GREATER, new BinaryComparator("95007".getBytes()));
scan.setFilter(rowFilter);2. Column Cluster Filter FamilyFilter
Filter familyFilter = new FamilyFilter(CompareOp.EQUAL, new BinaryComparator("info".getBytes()));
scan.setFilter(familyFilter);3. Column filter Qualifier Filter
Filter qualifierFilter = new QualifierFilter(CompareOp.EQUAL, new BinaryComparator("name".getBytes()));
scan.setFilter(qualifierFilter);4. Value Filter
Filter valueFilter = new ValueFilter(CompareOp.EQUAL, new SubstringComparator("male"));
scan.setFilter(valueFilter);5. Timestamps Filter
List<Long> list = new ArrayList<>(); list.add(1522469029503l); TimestampsFilter timestampsFilter = new TimestampsFilter(list); scan.setFilter(timestampsFilter);
Special filter
1. Single column value filter SingleColumnValueFilter -- returns the entire line that satisfies the criteria
SingleColumnValueFilter singleColumnValueFilter = new SingleColumnValueFilter(
"info".getBytes(), //Column Cluster
"name".getBytes(), //column
CompareOp.EQUAL,
new SubstringComparator("Liu Chen"));
//If not set to true, rows that do not contain the specified column will also return
singleColumnValueFilter.setFilterIfMissing(true);
scan.setFilter(singleColumnValueFilter);2. Single Column Value Exclude Filter
SingleColumnValueExcludeFilter singleColumnValueExcludeFilter = new SingleColumnValueExcludeFilter(
"info".getBytes(),
"name".getBytes(),
CompareOp.EQUAL,
new SubstringComparator("Liu Chen"));
singleColumnValueExcludeFilter.setFilterIfMissing(true);
scan.setFilter(singleColumnValueExcludeFilter);3. Prefix Filter - For row keys
PrefixFilter prefixFilter = new PrefixFilter("9501".getBytes());
scan.setFilter(prefixFilter);4. Column Prefix Filter
ColumnPrefixFilter columnPrefixFilter = new ColumnPrefixFilter("name".getBytes());
scan.setFilter(columnPrefixFilter);Page Filter
scan.setStartRow(startRow.getBytes()); scan.setMaxResultSize(pageSize);//Set how many pieces of data we scan PageFilter filter1 = new PageFilter(pageSize);