#.1Algorithms for Executing
1.External query
2.sorting Sort strategy
3.Merge strategy
#2.Algorithm for select operation
#3.Methods and Implementation of join operation
1. Algorithms for Executing External Queries:
- Sequential Scan: This algorithm scans the entire table sequentially, looking for matching records.
- Index Scan: This algorithm uses an index to quickly locate the desired records.
- Bitmap Index Scan: This algorithm uses a bitmap index to quickly identify matching records.
- Hash Join: This algorithm partitions the tables based on a hash function and performs the join operation on the matching partitions.
- Parallel Execution: This algorithm divides the query execution across multiple processors or nodes, each processing a subset of the data.
2. Sorting Sort Strategy:
- Bubble Sort: This algorithm compares adjacent elements and swaps them if they are in the wrong order, repeating this process until the entire list is sorted.
- Insertion Sort: This algorithm builds the final sorted array one element at a time by comparing each element with the ones before it and inserting it in the correct position.
- Selection Sort: This algorithm repeatedly finds the minimum element from the unsorted part of the array and swaps it with the first element.
- Quick Sort: This algorithm divides the array into two subarrays, according to a pivot element, and recursively sorts each subarray.
- Merge Sort: This algorithm divides the array into two halves, recursively sorts them, and then merges the two sorted halves.
3. Merge Strategy:
- Merge Sort: This algorithm divides the input into smaller subproblems, recursively sorts them, and then merges the sorted subproblems to produce the final sorted output.
- External Merge Sort: This algorithm is used for sorting large datasets that cannot fit into memory. It divides the data into smaller chunks, sorts them individually, and then merges them using external storage (such as disk).
4. Algorithm for Select Operation:
- Sequential Scan: This algorithm scans the entire table sequentially, applying a condition to filter out the desired records.
- Index Scan: This algorithm uses an index to quickly locate the desired records based on the condition specified in the query.
- Bitmap Index Scan: This algorithm uses a bitmap index to quickly identify the matching records based on the condition specified in the query.
5. Methods and Implementation of Join Operation:
- Nested Loop Join: This algorithm compares each record from one table with every record from the other table based on a specified condition.
- Hash Join: This algorithm partitions the tables based on a hash function and performs the join operation on the matching partitions.
- Merge Join: This algorithm sorts the two tables based on the join columns and then merges them together, identifying matching records.
- Sort-Merge Join: This algorithm first sorts the two tables based on the join columns and then performs a merge operation to identify matching records.