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This function for bit and bytea counts the set bits in the bit or byte string. Internally, we use the existing popcount functionality. For the name, after some discussion, we settled on bit_count, which also exists with this meaning in MySQL, Java, and Python. Author: David Fetter <david@fetter.org> Discussion: https://www.postgresql.org/message-id/flat/20201230105535.GJ13234@fetter.org
232 lines
7.6 KiB
SQL
232 lines
7.6 KiB
SQL
--
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-- BIT types
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--
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--
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-- Build tables for testing
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--
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CREATE TABLE BIT_TABLE(b BIT(11));
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INSERT INTO BIT_TABLE VALUES (B'10'); -- too short
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INSERT INTO BIT_TABLE VALUES (B'00000000000');
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INSERT INTO BIT_TABLE VALUES (B'11011000000');
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INSERT INTO BIT_TABLE VALUES (B'01010101010');
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INSERT INTO BIT_TABLE VALUES (B'101011111010'); -- too long
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--INSERT INTO BIT_TABLE VALUES ('X554');
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--INSERT INTO BIT_TABLE VALUES ('X555');
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SELECT * FROM BIT_TABLE;
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CREATE TABLE VARBIT_TABLE(v BIT VARYING(11));
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INSERT INTO VARBIT_TABLE VALUES (B'');
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INSERT INTO VARBIT_TABLE VALUES (B'0');
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INSERT INTO VARBIT_TABLE VALUES (B'010101');
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INSERT INTO VARBIT_TABLE VALUES (B'01010101010');
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INSERT INTO VARBIT_TABLE VALUES (B'101011111010'); -- too long
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--INSERT INTO VARBIT_TABLE VALUES ('X554');
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--INSERT INTO VARBIT_TABLE VALUES ('X555');
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SELECT * FROM VARBIT_TABLE;
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-- Concatenation
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SELECT v, b, (v || b) AS concat
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FROM BIT_TABLE, VARBIT_TABLE
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ORDER BY 3;
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-- Length
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SELECT b, length(b) AS lb
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FROM BIT_TABLE;
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SELECT v, length(v) AS lv
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FROM VARBIT_TABLE;
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-- Substring
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SELECT b,
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SUBSTRING(b FROM 2 FOR 4) AS sub_2_4,
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SUBSTRING(b FROM 7 FOR 13) AS sub_7_13,
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SUBSTRING(b FROM 6) AS sub_6
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FROM BIT_TABLE;
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SELECT v,
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SUBSTRING(v FROM 2 FOR 4) AS sub_2_4,
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SUBSTRING(v FROM 7 FOR 13) AS sub_7_13,
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SUBSTRING(v FROM 6) AS sub_6
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FROM VARBIT_TABLE;
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-- test overflow cases
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SELECT SUBSTRING('01010101'::bit(8) FROM 2 FOR 2147483646) AS "1010101";
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SELECT SUBSTRING('01010101'::bit(8) FROM -10 FOR 2147483646) AS "01010101";
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SELECT SUBSTRING('01010101'::bit(8) FROM -10 FOR -2147483646) AS "error";
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SELECT SUBSTRING('01010101'::varbit FROM 2 FOR 2147483646) AS "1010101";
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SELECT SUBSTRING('01010101'::varbit FROM -10 FOR 2147483646) AS "01010101";
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SELECT SUBSTRING('01010101'::varbit FROM -10 FOR -2147483646) AS "error";
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--- Bit operations
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DROP TABLE varbit_table;
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CREATE TABLE varbit_table (a BIT VARYING(16), b BIT VARYING(16));
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COPY varbit_table FROM stdin;
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X0F X10
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X1F X11
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X2F X12
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X3F X13
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X8F X04
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X000F X0010
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X0123 XFFFF
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X2468 X2468
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XFA50 X05AF
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X1234 XFFF5
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\.
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SELECT a, b, ~a AS "~ a", a & b AS "a & b",
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a | b AS "a | b", a # b AS "a # b" FROM varbit_table;
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SELECT a,b,a<b AS "a<b",a<=b AS "a<=b",a=b AS "a=b",
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a>=b AS "a>=b",a>b AS "a>b",a<>b AS "a<>b" FROM varbit_table;
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SELECT a,a<<4 AS "a<<4",b,b>>2 AS "b>>2" FROM varbit_table;
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DROP TABLE varbit_table;
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--- Bit operations
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DROP TABLE bit_table;
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CREATE TABLE bit_table (a BIT(16), b BIT(16));
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COPY bit_table FROM stdin;
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X0F00 X1000
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X1F00 X1100
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X2F00 X1200
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X3F00 X1300
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X8F00 X0400
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X000F X0010
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X0123 XFFFF
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X2468 X2468
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XFA50 X05AF
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X1234 XFFF5
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\.
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SELECT a,b,~a AS "~ a",a & b AS "a & b",
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a|b AS "a | b", a # b AS "a # b" FROM bit_table;
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SELECT a,b,a<b AS "a<b",a<=b AS "a<=b",a=b AS "a=b",
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a>=b AS "a>=b",a>b AS "a>b",a<>b AS "a<>b" FROM bit_table;
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SELECT a,a<<4 AS "a<<4",b,b>>2 AS "b>>2" FROM bit_table;
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DROP TABLE bit_table;
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-- The following should fail
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select B'001' & B'10';
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select B'0111' | B'011';
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select B'0010' # B'011101';
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-- More position tests, checking all the boundary cases
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SELECT POSITION(B'1010' IN B'0000101'); -- 0
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SELECT POSITION(B'1010' IN B'00001010'); -- 5
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SELECT POSITION(B'1010' IN B'00000101'); -- 0
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SELECT POSITION(B'1010' IN B'000001010'); -- 6
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SELECT POSITION(B'' IN B'00001010'); -- 1
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SELECT POSITION(B'0' IN B''); -- 0
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SELECT POSITION(B'' IN B''); -- 0
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SELECT POSITION(B'101101' IN B'001011011011011000'); -- 3
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SELECT POSITION(B'10110110' IN B'001011011011010'); -- 3
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SELECT POSITION(B'1011011011011' IN B'001011011011011'); -- 3
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SELECT POSITION(B'1011011011011' IN B'00001011011011011'); -- 5
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SELECT POSITION(B'11101011' IN B'11101011'); -- 1
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SELECT POSITION(B'11101011' IN B'011101011'); -- 2
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SELECT POSITION(B'11101011' IN B'00011101011'); -- 4
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SELECT POSITION(B'11101011' IN B'0000011101011'); -- 6
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SELECT POSITION(B'111010110' IN B'111010110'); -- 1
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SELECT POSITION(B'111010110' IN B'0111010110'); -- 2
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SELECT POSITION(B'111010110' IN B'000111010110'); -- 4
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SELECT POSITION(B'111010110' IN B'00000111010110'); -- 6
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SELECT POSITION(B'111010110' IN B'11101011'); -- 0
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SELECT POSITION(B'111010110' IN B'011101011'); -- 0
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SELECT POSITION(B'111010110' IN B'00011101011'); -- 0
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SELECT POSITION(B'111010110' IN B'0000011101011'); -- 0
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SELECT POSITION(B'111010110' IN B'111010110'); -- 1
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SELECT POSITION(B'111010110' IN B'0111010110'); -- 2
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SELECT POSITION(B'111010110' IN B'000111010110'); -- 4
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SELECT POSITION(B'111010110' IN B'00000111010110'); -- 6
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SELECT POSITION(B'111010110' IN B'000001110101111101011'); -- 0
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SELECT POSITION(B'111010110' IN B'0000001110101111101011'); -- 0
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SELECT POSITION(B'111010110' IN B'000000001110101111101011'); -- 0
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SELECT POSITION(B'111010110' IN B'00000000001110101111101011'); -- 0
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SELECT POSITION(B'111010110' IN B'0000011101011111010110'); -- 14
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SELECT POSITION(B'111010110' IN B'00000011101011111010110'); -- 15
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SELECT POSITION(B'111010110' IN B'0000000011101011111010110'); -- 17
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SELECT POSITION(B'111010110' IN B'000000000011101011111010110'); -- 19
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SELECT POSITION(B'000000000011101011111010110' IN B'000000000011101011111010110'); -- 1
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SELECT POSITION(B'00000000011101011111010110' IN B'000000000011101011111010110'); -- 2
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SELECT POSITION(B'0000000000011101011111010110' IN B'000000000011101011111010110'); -- 0
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-- Shifting
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CREATE TABLE BIT_SHIFT_TABLE(b BIT(16));
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INSERT INTO BIT_SHIFT_TABLE VALUES (B'1101100000000000');
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INSERT INTO BIT_SHIFT_TABLE SELECT b>>1 FROM BIT_SHIFT_TABLE;
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INSERT INTO BIT_SHIFT_TABLE SELECT b>>2 FROM BIT_SHIFT_TABLE;
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INSERT INTO BIT_SHIFT_TABLE SELECT b>>4 FROM BIT_SHIFT_TABLE;
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INSERT INTO BIT_SHIFT_TABLE SELECT b>>8 FROM BIT_SHIFT_TABLE;
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SELECT POSITION(B'1101' IN b),
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POSITION(B'11011' IN b),
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b
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FROM BIT_SHIFT_TABLE ;
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SELECT b, b >> 1 AS bsr, b << 1 AS bsl
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FROM BIT_SHIFT_TABLE ;
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SELECT b, b >> 8 AS bsr8, b << 8 AS bsl8
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FROM BIT_SHIFT_TABLE ;
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SELECT b::bit(15), b::bit(15) >> 1 AS bsr, b::bit(15) << 1 AS bsl
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FROM BIT_SHIFT_TABLE ;
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SELECT b::bit(15), b::bit(15) >> 8 AS bsr8, b::bit(15) << 8 AS bsl8
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FROM BIT_SHIFT_TABLE ;
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CREATE TABLE VARBIT_SHIFT_TABLE(v BIT VARYING(20));
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INSERT INTO VARBIT_SHIFT_TABLE VALUES (B'11011');
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INSERT INTO VARBIT_SHIFT_TABLE SELECT CAST(v || B'0' AS BIT VARYING(6)) >>1 FROM VARBIT_SHIFT_TABLE;
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INSERT INTO VARBIT_SHIFT_TABLE SELECT CAST(v || B'00' AS BIT VARYING(8)) >>2 FROM VARBIT_SHIFT_TABLE;
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INSERT INTO VARBIT_SHIFT_TABLE SELECT CAST(v || B'0000' AS BIT VARYING(12)) >>4 FROM VARBIT_SHIFT_TABLE;
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INSERT INTO VARBIT_SHIFT_TABLE SELECT CAST(v || B'00000000' AS BIT VARYING(20)) >>8 FROM VARBIT_SHIFT_TABLE;
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SELECT POSITION(B'1101' IN v),
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POSITION(B'11011' IN v),
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v
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FROM VARBIT_SHIFT_TABLE ;
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SELECT v, v >> 1 AS vsr, v << 1 AS vsl
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FROM VARBIT_SHIFT_TABLE ;
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SELECT v, v >> 8 AS vsr8, v << 8 AS vsl8
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FROM VARBIT_SHIFT_TABLE ;
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DROP TABLE BIT_SHIFT_TABLE;
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DROP TABLE VARBIT_SHIFT_TABLE;
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-- Get/Set bit
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SELECT get_bit(B'0101011000100', 10);
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SELECT set_bit(B'0101011000100100', 15, 1);
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SELECT set_bit(B'0101011000100100', 16, 1); -- fail
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-- Overlay
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SELECT overlay(B'0101011100' placing '001' from 2 for 3);
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SELECT overlay(B'0101011100' placing '101' from 6);
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SELECT overlay(B'0101011100' placing '001' from 11);
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SELECT overlay(B'0101011100' placing '001' from 20);
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-- bit_count
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SELECT bit_count(B'0101011100'::bit(10));
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SELECT bit_count(B'1111111111'::bit(10));
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-- This table is intentionally left around to exercise pg_dump/pg_upgrade
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CREATE TABLE bit_defaults(
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b1 bit(4) DEFAULT '1001',
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b2 bit(4) DEFAULT B'0101',
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b3 bit varying(5) DEFAULT '1001',
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b4 bit varying(5) DEFAULT B'0101'
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);
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\d bit_defaults
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INSERT INTO bit_defaults DEFAULT VALUES;
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TABLE bit_defaults;
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