Soldering other precipitation may wash the lead into the groundwater. Unfortunately, most lead-free solders are not eutectic formulations, melting at around , making it more difficult to create reliable joints with them. Other common solders include low-temperature formulations (often containing bismuth), which are often used to join previously-soldered assemblies without unsoldering earlier connections, and high-temperature formulations (usually containing silver) which are used for high-temperature operation or for first assembly of items which must not become unsoldered during subsequent operations. Alloying silver with other metals changes the melting point, adhesion and wetting characteristics, and tensile strength. Of all the brazing alloys, silver
Hash join As with the anti-join, semi-join can also be left and right: The records are returned right after they produced a hit. The actual records from the hash table are ignored. This is more efficient when the IN table is smaller than the FROM table With this algorithm, each record from the hash table (that is, FROM table) can only be returned once, since it is removed after being returned. This is more efficient when the IN table is larger than the FROM table Hash join The hash join is an example of a join algorithm and is used in the